strut forks
- Thread starter cubdrvr
- Start date
cubpilot2
SPONSOR
Anchorage Alaska
Maybe I am confused here?? Not a first time.
The struts are always referred to as "life time" but.....
In trying to sift through AD 99-01-05
As I have been reading it in Par (4) says that the installation of the the sealed struts and larger forks constitutes terminating action for the inspection requirements of both par. (a) and (b)
Further down in par. (B) still calls for the replacement at 2000 hrs etc.
Can't see where you get away from it.
How's everyone else reading this???
The struts are always referred to as "life time" but.....
In trying to sift through AD 99-01-05
As I have been reading it in Par (4) says that the installation of the the sealed struts and larger forks constitutes terminating action for the inspection requirements of both par. (a) and (b)
Further down in par. (B) still calls for the replacement at 2000 hrs etc.
Can't see where you get away from it.
How's everyone else reading this???
Steve Pierce
BENEFACTOR
Graham, TX
(a) is the strut and (b) is the fork. "Installation of these assemblies constitute terminating action for the inspection requirements of both paragraphs (a) and (b) of this AD."
(4) Install new sealed wing lift strut assemblies,
part numbers as specified in Piper SB No. 528D and Piper SB
No. 910A (or FAA-approved equivalent part numbers) on each
wing as specified in the Instructions section in Part II of
the above-referenced SB's. These sealed wing lift strut
assemblies also include the wing lift strut forks.
Installation of these assemblies constitute terminating
action for the inspection requirements of both paragraphs
(a) and (b) of this AD.
(a) For all affected airplane models, within 1 calendar
month after the effective date of this AD or within 24
calendar months after the last inspection accomplished in
accordance with AD 93-10-06 (superseded by this action),
whichever occurs later, remove the wing lift struts in
accordance with Piper Service Bulletin (SB) No. 528D, dated
October 19, 1990, or Piper SB No. 910A, dated October 10,
1989, as applicable, and accomplish one of the following
(the actions in either paragraph (a)(1), (a)(2), (a)(3),
(a)(4), or (a)(5); including subparagraphs, of this AD):...
(b) For all affected airplane models, except for Models
PA-25, PA-25-235, and PA-25-260, within the next 100 hours
time-in-service (TIS) after the effective date of this AD or
within 500 hours TIS after the last inspection accomplished
in accordance with AD 93-10-06 (superseded by this action),
whichever occurs later, remove the wing lift strut forks,
and accomplish one of the following (the actions in either
paragraph (b)(1), (b)(2), (b)(3), (b)(4), or (b)(5);
including subparagraphs, of this AD):..
(4) Install new sealed wing lift strut assemblies,
part numbers as specified in Piper SB No. 528D and Piper SB
No. 910A (or FAA-approved equivalent part numbers) on each
wing as specified in the Instructions section in Part II of
the above-referenced SB's. These sealed wing lift strut
assemblies also include the wing lift strut forks.
Installation of these assemblies constitute terminating
action for the inspection requirements of both paragraphs
(a) and (b) of this AD.
(a) For all affected airplane models, within 1 calendar
month after the effective date of this AD or within 24
calendar months after the last inspection accomplished in
accordance with AD 93-10-06 (superseded by this action),
whichever occurs later, remove the wing lift struts in
accordance with Piper Service Bulletin (SB) No. 528D, dated
October 19, 1990, or Piper SB No. 910A, dated October 10,
1989, as applicable, and accomplish one of the following
(the actions in either paragraph (a)(1), (a)(2), (a)(3),
(a)(4), or (a)(5); including subparagraphs, of this AD):...
(b) For all affected airplane models, except for Models
PA-25, PA-25-235, and PA-25-260, within the next 100 hours
time-in-service (TIS) after the effective date of this AD or
within 500 hours TIS after the last inspection accomplished
in accordance with AD 93-10-06 (superseded by this action),
whichever occurs later, remove the wing lift strut forks,
and accomplish one of the following (the actions in either
paragraph (b)(1), (b)(2), (b)(3), (b)(4), or (b)(5);
including subparagraphs, of this AD):..
Steve Pierce
BENEFACTOR
Graham, TX
Paragraph b is the requirement of the fork inspection. If you install the listed struts which are the ones with the larger forks it eliminates inspections of paragraph b.
"(3) Install new sealed wing lift strut assemblies,
part numbers as specified in Piper SB No. 528D and Piper SB
No. 910A (or FAA-approved equivalent part numbers) on each
wing, as specified in the Instructions section in Part II of
the above-referenced SB's.
(i) This installation may have "already
been accomplished" through the actions specified in paragraph
(a)(4) of this AD.
(ii) No repetitive inspections are required
after installing these sealed wing lift strut assemblies."
FOR FURTHER INFORMATION CONTACT:
William O. Herderich, Aerospace Engineer, FAA, Atlanta
Certification Office, One Crown Center,
1895 Phoenix Boulevard, suite 450, Atlanta, Georgia 30349;
telephone: (770) 703-6084; facsimile: (770) 703-6097.
"(3) Install new sealed wing lift strut assemblies,
part numbers as specified in Piper SB No. 528D and Piper SB
No. 910A (or FAA-approved equivalent part numbers) on each
wing, as specified in the Instructions section in Part II of
the above-referenced SB's.
(i) This installation may have "already
been accomplished" through the actions specified in paragraph
(a)(4) of this AD.
(ii) No repetitive inspections are required
after installing these sealed wing lift strut assemblies."
FOR FURTHER INFORMATION CONTACT:
William O. Herderich, Aerospace Engineer, FAA, Atlanta
Certification Office, One Crown Center,
1895 Phoenix Boulevard, suite 450, Atlanta, Georgia 30349;
telephone: (770) 703-6084; facsimile: (770) 703-6097.
Steve Pierce
BENEFACTOR
Graham, TX
99-01-05 THE NEW PIPER AIRCRAFT, INC.: Amendment
39-10972; Docket No. 96-CE-72-AD; Supersedes AD 93-10-06, Amendment
39-8536.
Applicability: The following model and serial number
airplanes, certificated in any category:
Models Serial Numbers
TG-8 (Army TG-8, Navy XLNP-1) All serial numbers
E-2 and F-2 All serial numbers
J3C-40, J3C-50, J3C-50S, (Army L-4, L-4B, All serial numbers
L-4H, and L-4J), J3C-65 (Navy NE-1 and
NE-2), J3C-65S J3F-50, J3F-50S, J3F-60,
J3F-60S, J3F-65 (Army L-4D), J3F-65S,
J3L, J3L-S, J3L-65 (Army L-4C), and J3L-65S
J4, J4A, J4A-S, and J4E (Army L-4E) 4-401 through 4-1649
J5A (Army L-4F), J5A-80, J5B, (Army L-4G), All serial numbers
J5C, L-14, AE-1, and HE-1
PA-11 and PA-11S 11-1 through 11-1678
PA-12 and PA-12S 12-1 through 12-4036
PA-14 14-1 through 14-523
PA-15 15-1 through 15-388
PA-16 and PA-16S 16-1 through 16-736
PA-17 17-1 through 17-215
PA-18, PA-18S, PA-18 "105" (Special), 18-1 through 18-8309025,
PA-18S "105" (Special) PA-18A, PA-18 "125", 189001 through 1809032,
(Army L-21A), PA-18S "125", PA-18AS "125", and 1809034 through
PA-18 "135" (Army L-21B), PA-18A "135", 1809040
PA-18S "135", PA-18AS "135", PA-18 "150",
PA-18A "150", PA-18S "150", PA-18AS "150",
PA-18A (Restricted),PA-18A "135" (Restricted),
and PA-18A "150" (Restricted)
PA-19 (Army L-18C), and PA-19S 19-1, 19-2, and 19-3
PA-20, PA-20S, PA-20 "115", PA-20S "115", 20-1 through 20-1121
PA-20 "135", and PA-20S "135"
PA-22, PA-22-108, PA-22-135, PA-22S-135, 22-1 through 22-9848
PA-22-150, PA-22S-150, PA-22-160, and
PA-22S-160
PA-25, PA-25-235, and PA-25-260 25-1 through 25-8156024
NOTE 1: This AD applies to each airplane identified in
the preceding applicability provision, regardless of whether
it has been modified, altered, or repaired in the area
subject to the requirements of this AD. For airplanes that
have been modified, altered, or repaired so that the
performance of the requirements of this AD is affected, the
owner/operator must request approval for an alternative
method of compliance in accordance with paragraph (f) of
this AD. The request should include an assessment of the
effect of the modification, alteration, or repair on the
unsafe condition addressed by this AD; and, if the unsafe
condition has not been eliminated, the request should
include specific proposed actions to address it.
Compliance: Required as indicated in the body of this
AD, unless already accomplished.
To prevent in-flight separation of the wing from the
airplane caused by corroded wing lift struts or cracked wing
lift strut forks, which could result in loss of control of
the airplane, accomplish the following:
NOTE 2: The paragraph structure of this AD is as follows:
Level 1: (a), (b), (c), etc.
Level 2: (1), (2), (3), etc.
Level 3: (i), (ii), (iii), etc.
Level 4: (A), (B), (C), etc.
Level 2, Level 3, and Level 4 structures are designations of
the Level 1 paragraph they immediately follow.
(a) For all affected airplane models, within 1 calendar
month after the effective date of this AD or within 24
calendar months after the last inspection accomplished in
accordance with AD 93-10-06 (superseded by this action),
whichever occurs later, remove the wing lift struts in
accordance with Piper Service Bulletin (SB) No. 528D, dated
October 19, 1990, or Piper SB No. 910A, dated October 10,
1989, as applicable, and accomplish one of the following
(the actions in either paragraph (a)(1), (a)(2), (a)(3),
(a)(4), or (a)(5); including subparagraphs, of this AD):
(1) Inspect the wing lift struts for corrosion
in accordance with the "Instructions" section in Part I of
either Piper SB No. 528D, dated October 19, 1990, or Piper
SB No. 910A, dated October 10, 1989, as applicable.
(i) If no perceptible dents (as defined
in the above SB's) are found in the wing lift strut and no
corrosion is externally visible, prior to further flight,
apply corrosion inhibitor to each strut in accordance with
whichever of the above SB's that is applicable. Reinspect
the lift struts at intervals not to exceed 24 calendar
months and accomplish any of the requirements of paragraph
(a) of this AD, including all subparagraphs.
(ii) If a perceptible dent (as defined
in the above SB's) is found in the wing lift strut or external
corrosion is found, prior to further flight, accomplish one
of the installations (and subsequent actions presented in
each paragraph) specified in paragraphs (a)(3), (a)(4), or
(a)(5) of this AD.
(2) Inspect the wing lift struts for corrosion in
accordance with the Appendix to this AD. The inspection
procedures in this Appendix must be accomplished by a Level
2 inspector certified using the guidelines established by
the American Society for Non-destructive Testing, or MIL-
STD-410.
(i) If no corrosion is found that is
externally visible and all requirements in the Appendix to this
AD are met, prior to further flight, apply corrosion inhibitor to
each strut in accordance with whichever of the above SB's
that is applicable. Reinspect the lift struts at intervals
not to exceed 24 calendar months and accomplish any of the
requirements of paragraph (a) of this AD, including all
subparagraphs.
(ii) If external corrosion is found or if
any of the requirements in the Appendix of this AD are not met,
prior to further flight, accomplish one of the installations
(and subsequent actions presented in each paragraph)
specified in paragraphs (a)(3), (a)(4), or (a)(5) of this
AD.
(3) Install original equipment manufacturer (OEM)
part number wing struts (or FAA-approved equivalent part
numbers) that have been inspected in accordance with the
specifications presented in either paragraph (a)(1) or
(a)(2) of this AD, and are found to be airworthy according
to the inspection requirements included in these paragraphs.
Thereafter, inspect these wing lift struts at intervals not
to exceed 24 calendar months in accordance with the
specifications presented in either paragraph (a)(1) or
(a)(2) of this AD.
(4) Install new sealed wing lift strut assemblies,
part numbers as specified in Piper SB No. 528D and Piper SB
No. 910A (or FAA-approved equivalent part numbers) on each
wing as specified in the Instructions section in Part II of
the above-referenced SB's. These sealed wing lift strut
assemblies also include the wing lift strut forks.
Installation of these assemblies constitute terminating
action for the inspection requirements of both paragraphs
(a) and (b) of this AD.
(5) Install F. Atlee Dodge wing lift strut
assemblies in accordance with F. Atlee Dodge Installation
Instructions No. 3233-I for Modified Piper Wing Lift Struts
(Supplemental Type Certificate (STC) SA4635NM), dated
February 1, 1991. Thereafter, inspect these wing lift
struts at intervals not to exceed 60 calendar months in
accordance with the specifications presented in paragraph
(a)(1) or (a)(2) of this AD.
(b) For all affected airplane models, except for Models
PA-25, PA-25-235, and PA-25-260, within the next 100 hours
time-in-service (TIS) after the effective date of this AD or
within 500 hours TIS after the last inspection accomplished
in accordance with AD 93-10-06 (superseded by this action),
whichever occurs later, remove the wing lift strut forks,
and accomplish one of the following (the actions in either
paragraph (b)(1), (b)(2), (b)(3), (b)(4), or (b)(5);
including subparagraphs, of this AD):
(1) Inspect the wing lift strut forks using FAA-
approved magnetic particle procedures.
(i) If no cracks are found, reinspect at
intervals not to exceed 500 hours TIS provided that the
replacement requirements of paragraphs (b)(1)(ii)(B) and
(b)(1)(ii)(C) of this AD have been met.
(ii) Replace the wing lift strut forks at
whichever of the following is applicable:
(A) If cracks are found on any wing
lift strut fork: Prior to further flight;
(B) If the airplane is equipped with
floats or has been equipped with floats within the last 2,000 hours
TIS and no cracks are found during the above inspections:
Upon accumulating 1,000 hours TIS on the wing lift strut
forks or within the next 100 hours TIS, whichever occurs
later; or
(C) If the airplane has not been
equipped with floats within the last 2,000 hours TIS and no cracks
are found during the above inspections: Upon accumulating 2,000
hours TIS on the wing lift strut forks or within the next
100 hours TIS, whichever occurs later.
(iii) Replacement parts shall be of the
same part numbers of the existing part (or FAA-approved equivalent
part numbers) and shall be manufactured with rolled threads.
Lift strut forks manufactured with machined (cut) threads
shall not be utilized.
(iv) The 500-hour TIS interval repetitive
inspections are still required when the above replacements
are accomplished.
(2) Install new OEM part number wing lift strut
forks (or FAA-approved equivalent part numbers). Reinspect
and replace these wing lift strut forks at the intervals
specified in paragraphs (b)(1)(i), (b)(1)(ii), (b)(1)(iii),
and (b)(1)(iv), including all subparagraphs, of this AD.
(3) Install new sealed wing lift strut assemblies,
part numbers as specified in Piper SB No. 528D and Piper SB
No. 910A (or FAA-approved equivalent part numbers) on each
wing, as specified in the Instructions section in Part II of
the above-referenced SB's.
(i) This installation may have "already
been accomplished" through the actions specified in paragraph
(a)(4) of this AD.
(ii) No repetitive inspections are required
after installing these sealed wing lift strut assemblies.
(4) Install Jensen Aircraft wing lift strut fork
assemblies as specified in the STC's presented in the
paragraphs that follow, as applicable, in accordance with
Jensen Aircraft Installation Instructions for Modified Lift
Strut Fittings, which incorporates the following pages:
Pages Revision Level Date
1 and 5 Original Issue July 15, 1983
2, 4, and 6 Revision No. 1 March 30, 1984
a and 3 Revision No. 2 April 20, 1984
No repetitive inspections are required after installing
these Jensen Aircraft wing lift strut fork assemblies;
however, repetitive inspections of the lift strut are
required as specified in paragraph (a)(1), (a)(2), or (a)(3)
of this AD:
(i) For Models PA-12 and PA-12S airplanes:
STC SA1583NM;
(ii) For Model PA-14 airplanes:
STC SA1584NM;
(iii) For the Models PA-16 and PA-16S
airplanes: STC SA1590NM;
(iv) For the Models PA-18, PA-18S,
189001 PA-18 "105" (Special), PA-18S "105" (Special), PA-18A,
PA-18 "125" (Army L-21A), PA-18S "125", PA-18AS "125", PA-18 "135"
(Army L-21B), PA-18A "135", PA-18S "135", PA-18S "135", PA-18AS
"135", PA-18 "150", PA-18A "150", PA-18S "150", PA-18AS
"150", PA-18A (Restricted), PA-18A "135" (Restricted), and
PA-18A "150" (Restricted) airplanes: STC SA1585NM;
(v) For the Models PA-20, PA-20S,
PA-20 "115", PA-20S "115", PA-20 "135", and PA-20S "135"
airplanes: STC SA1586NM; and
(vi) For the Model PA-22 airplanes:
STC SA1587NM.
(5) Install F. Atlee Dodge wing lift strut
assemblies in accordance with F. Atlee Dodge Installation
Instructions No. 3233-I for Modified Piper Wing Lift Struts
(STC SA4635NM), dated February 1, 1991.
(i) No repetitive inspections of the wing
lift strut forks are required when these assemblies are
installed.
(ii) This installation may have "already
been accomplished" through the actions specified in paragraph
(a)(5) of this AD.
(c) If holes are drilled, in either one of the
scenarios presented in paragraphs (c)(1) and (c)(2) of this
AD, to attach cuffs, door clips, or other hardware, inspect
the wing lift struts at intervals not to exceed 24 calendar
months using the procedures specified in paragraphs (a)(1)
and (a)(2), including all subparagraphs, of this AD:
(1) Wing lift strut assemblies installed in
accordance with (a)(4) or (b)(3) of this AD; or
(2) F. Atlee Dodge wing lift strut assemblies
installed in accordance with paragraph (a)(5) or (b)(5) of
this AD.
(d) For all affected airplane models, within 1 calendar
month after the effective date of this AD or within 24
calendar months after the last inspection accomplished in
accordance with AD 93-10-06 (superseded by this action),
whichever occurs later, and thereafter prior to further
flight after the installation of any lift strut assembly,
accomplish one of the following:
(1) Install "NO STEP" decal, Piper part number
(P/N) 80944-02, on each wing lift strut approximately 6 inches
from the bottom of the struts in a way that the letters can
be read when entering and exiting the aircraft; or
(2) Paint the statement "NO STEP" approximately 6
inches from the bottom of the struts in a way that the
letters can be read when entering and exiting the aircraft.
Use a minimum of 1-inch letters using a color that contrasts
with the color of the airplane.
(e) Special flight permits may be issued in accordance
with sections 21.197 and 21.199 of the Federal Aviation
Regulations (14 CFR 21.197 and 21.199) to operate the
airplane to a location where the requirements of this AD can
be accomplished.
(f) An alternative method of compliance or adjustment
of the initial or repetitive compliance times that provides
an equivalent level of safety may be approved by the
Manager, Atlanta Aircraft Certification Office (ACO),
One Crown Center, 1895 Phoenix Boulevard, suite 450,
Atlanta, Georgia 30349.
(1) The request shall be forwarded through an
appropriate FAA Maintenance Inspector, who may add comments
and then send it to the Manager, Atlanta ACO.
(2) Alternative methods of compliance approved in
accordance with AD 93-10-06, Amendment 39-8536, are
considered approved as alternative methods of compliance for
this AD.
NOTE 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may
be obtained from the Atlanta Aircraft Certification Office.
(g) The inspections required by this AD shall be done
in accordance with Piper Service Bulletin No. 528D, dated
October 19, 1990, and Piper Service Bulletin No. 910A, dated
October 10, 1989. The installation required by this AD
shall be done in accordance with F. Atlee Dodge Installation
Instructions No. 3233-I for Modified Piper Wing Lift Struts
(Supplemental Type Certificate (STC) SA4635NM), dated
February 1, 1991, and Jensen Aircraft Installation
Instructions for Modified Lift Strut Fittings, which
incorporates the following pages:
Pages Revision Level Date
1 and 5 Original Issue July 15, 1983
2, 4, and 6 Revision No. 1 March 30, 1984
a and 3 Revision No. 2 April 20, 1984
This incorporation by reference was approved by the Director
of the Federal Register in accordance with 5 U.S.C. 552(a)
and 1 CFR part 51. The service bulletins referenced in this
AD may be obtained from The New Piper Aircraft, Inc.,
Customer Services, 2926 Piper Drive, Vero Beach, Florida
32960. Copies of the instructions to the Jensen Aircraft
STC's may be obtained from Jensen Aircraft, 9225 County Road
140, Salida, Colorado 81201. Copies of the instructions to
the F. Atlee Dodge STC may be obtained from F. Atlee Dodge,
Aircraft Services, Inc., P.O. Box 190409, Anchorage, Alaska
99519-0409. Copies may be inspected at the FAA, Central
Region, Office of the Regional Counsel, Room 1558, 601 E.
12th Street, Kansas City, Missouri, or at the Office of the
Federal Register, 800 North Capitol Street, NW, suite 700,
Washington, DC.
(h) This amendment supersedes AD 93-10-06, Amendment
39-8536.
(i) This amendment becomes effective on February 8,
1999.
FOR FURTHER INFORMATION CONTACT:
William O. Herderich, Aerospace Engineer, FAA, Atlanta
Certification Office, One Crown Center,
1895 Phoenix Boulevard, suite 450, Atlanta, Georgia 30349;
telephone: (770) 703-6084; facsimile: (770) 703-6097.
**************************************************************
APPENDIX TO AD 99-01-05; AMENDMENT 39-10972;
DOCKET NO. 96-CE-72-AD
PROCEDURES AND REQUIREMENTS
FOR ULTRASONIC INSPECTION OF PIPER WING LIFT STRUTS
Equipment Requirements
1. A portable ultrasonic thickness gauge or flaw detector
with echo-to-echo digital thickness readout capable of
reading to 0.001-inch and an A-trace waveform display will
be needed to accomplish this inspection.
2. An ultrasonic probe with the following specifications
will be needed to accomplish this inspection: 10 MHz (or
higher), 0.283-inch (or smaller) diameter dual element or
delay line transducer designed for thickness gauging. The
transducer and ultrasonic system shall be capable of
accurately measuring the thickness of AISI 4340 steel down
to 0.020-inch. An accuracy of +/- 0.002-inch throughout a
0.020-inch to 0.050-inch thickness range while calibrating
shall be the criteria for acceptance.
3. Either a precision machined step wedge made of 4340
steel (or similar steel with equivalent sound velocity) or
at least three shim samples of same material will be needed
to accomplish this inspection. One thickness of the step
wedge or shim shall be less than or equal to 0.020-inch, one
shall be greater than or equal to 0.050-inch, and at least
one other step or shim shall be between these two values.
4. Glycerin, light oil, or similar non-water based
ultrasonic couplants are recommended in the setup and
inspection procedures. Water-based couplants, containing
appropriate corrosion inhibitors, may be utilized, provided
they are removed from both the reference standards and the
test item after the inspection procedure is completed and
adequate corrosion prevention steps are then taken to
protect these items.
NOTE: Couplant is defined as "a substance used between
the face of the transducer and test surface to improve
transmission of ultrasonic energy across the
transducer/strut interface."
NOTE: If surface roughness due to paint loss or
corrosion is present, the surface should be sanded or
polished smooth before testing to assure a consistent and
smooth surface for making contact with the transducer. Care
shall be taken to remove a minimal amount of structural
material. Paint repairs may be necessary after the
inspection to prevent further corrosion damage from
occurring. Removal of surface irregularities will enhance
the accuracy of the inspection technique.
Instrument Setup
1. Set up the ultrasonic equipment for thickness
measurements as specified in the instrument's user's manual.
Because of the variety of equipment available to perform
ultrasonic thickness measurements, some modification to this
general setup procedure may be necessary. However, the
tolerance requirement of step 13 and the record keeping
requirement of step 14, must be satisfied.
2. If battery power will be employed, check to see that
the battery has been properly charged. The testing will
take approximately two hours. Screen brightness and
contrast should be set to match environmental conditions.
3. Verify that the instrument is set for the type of
transducer being used, i.e. single or dual element, and that
the frequency setting is compatible with the transducer.
4. If a removable delay line is used, remove it and place
a drop of couplant between the transducer face and the delay
line to assure good transmission of ultrasonic energy.
Reassemble the delay line transducer and continue.
5. Program a velocity of 0.231-inch/microsecond into the
ultrasonic unit unless an alternative instrument calibration
procedure is used to set the sound velocity.
6. Obtain a step wedge or steel shims per item 3 of the
Equipment Requirements. Place the probe on the thickest
sample using couplant. Rotate the transducer slightly back
and forth to "ring" the transducer to the sample. Adjust
the delay and range settings to arrive at an A-trace signal
display with the first backwall echo from the steel near the
left side of the screen and the second backwall echo near
the right of the screen. Note that when a single element
transducer is used, the initial pulse and the delay
line/steel interface will be off of the screen to the left.
Adjust the gain to place the amplitude of the first backwall
signal at approximately 80% screen height on the A-trace.
7. "Ring" the transducer on the thinnest step or shim
using couplant. Select positive half-wave rectified,
negative half-wave rectified, or filtered signal display to
obtain the cleanest signal. Adjust the pulse voltage, pulse
width, and damping to obtain the best signal resolution.
These settings can vary from one transducer to another and
are also user dependent.
8. Enable the thickness gate, and adjust the gate so
that it starts at the first backwall echo and ends at the
second backwall echo. (Measuring between the first and
second backwall echoes will produce a measurement of the
steel thickness that is not affected by the paint layer on
the strut). If instability of the gate trigger occurs,
adjust the gain, gate level, and/or damping to stabilize the
thickness reading.
9. Check the digital display reading and if it does
not agree with the known thickness of the thinnest thickness,
follow your instrument's calibration recommendations to
produce the correct thickness reading. When a single
element transducer is used this will usually involve
adjusting the fine delay setting.
10. Place the transducer on the thickest step of shim
using couplant. Adjust the thickness gate width so that the
gate is triggered by the second backwall reflection of the
thick section. If the digital display does not agree with
the thickest thickness, follow your instruments calibration
recommendations to produce the correct thickness reading. A
slight adjustment in the velocity may be necessary to get
both the thinnest and the thickest reading correct.
Document the changed velocity value.
11. Place couplant on an area of the lift strut which
is thought to be free of corrosion and "ring" the transducer
to surface. Minor adjustments to the signal and gate
settings may be required to account for coupling
improvements resulting from the paint layer. The thickness
gate level should be set just high enough so as not to be
triggered by irrelevant signal noise. An area on the upper
surface of the lift strut above the inspection area would be
a good location to complete this step and should produce a
thickness reading between 0.034-inch and 0.041-inch.
12. Repeat steps 8, 9, 10, and 11 until both thick and
thin shim measurements are within tolerance and the lift
strut measurement is reasonable and steady.
13. Verify that the thickness value shown in the
digital display is within +/- 0.002-inch of the correct
value for each of the three or more steps of the setup wedge
or shims. Make no further adjustments to the instrument
settings.
14. Record the ultrasonic versus actual thickness of
all wedge steps or steel shims available as a record of
setup.
Inspection Procedure
1. Clean the lower 18 inches of the wing lift struts
using a cleaner that will remove all dirt and grease. Dirt
and grease will adversely affect the accuracy of the
inspection technique. Light sanding or polishing may also
be required to reduce surface roughness as noted in the
Equipment Requirements section.
2. Using a flexible ruler, draw a 1/4-inch grid on the
surface of the first 11 inches from the lower end of the
strut as shown in Piper Service Bulletin No. 528D or 910A,
as applicable. This can be done using a soft (#2) pencil
and should be done on both faces of the strut. As an
alternative to drawing a complete grid, make two rows of
marks spaced every 1/4-inch across the width of the strut.
One row of marks should be about 11 inches from the lower
end of the strut, and the second row should be several
inches away where the strut starts to narrow. Lay the
flexible ruler between respective tick marks of the two rows
and use tape or a rubber band to keep the ruler in place.
See Figure 1.
ILLUSTRATION (Figure 1)
3. Apply a generous amount of couplant inside each of the
square areas or along the edge of the ruler. Re-application
of couplant may be necessary.
4. Place the transducer inside the first square area of
the drawn grid or at the first 1/4-inch mark on the ruler
and "ring" the transducer to the strut. When using a dual
element transducer, be very careful to record the thickness
value with the axis of the transducer elements perpendicular
to any curvature in the strut. If this is not done, loss of
signal or inaccurate readings can result.
5. Take readings inside each square on the grid or at
1/4-inch increments along the ruler and record the results.
When taking a thickness reading, rotate the transducer
slightly back and forth and experiment with the angle of
contact to produce the lowest thickness reading possible.
Pay close attention to the A-scan display to assure that the
thickness gate is triggering off of maximized backwall
echoes.
NOTE: A reading shall not exceed .041-inch. If a
reading exceeds .041-inch, repeat steps 13 and 14 of the
Instrument Setup section before proceeding further.
6. If the A-trace is unsteady or the thickness reading is
clearly wrong, adjust the signal gain and/or gate setting to
obtain reasonable and steady readings. If any instrument
setting is adjusted, repeat steps 13 and 14 of the
Instrument Setup section before proceeding further.
7. In areas where obstructions are present, take a data
point as close to the correct area as possible.
NOTE: The strut wall contains a fabrication bead at
approximately 40% of the strut chord. The bead may
interfere with accurate measurements in that specific
location.
8. A measurement of 0.024-inch or less shall require
replacement of the strut prior to further flight
9. If at any time during testing an area is encountered
where a valid thickness measurement cannot be obtained due
to a loss of signal strength or quality, the area shall be
considered suspect. These areas may have a remaining wall
thickness of less than 0.020-inch, which is below the range
of this setup, or they may have small areas of localized
corrosion or pitting present. The latter case will result
in a reduction in signal strength due to the sound being
scattered from the rough surface and may result in a signal
that includes echoes from the pits as well as the backwall.
The suspect area(s) shall be tested with a Maule "Fabric
Tester" as specified in Piper Service Bulletin No. 528D or
910A.
10. Record the lift strut inspection in the aircraft
log book.
39-10972; Docket No. 96-CE-72-AD; Supersedes AD 93-10-06, Amendment
39-8536.
Applicability: The following model and serial number
airplanes, certificated in any category:
Models Serial Numbers
TG-8 (Army TG-8, Navy XLNP-1) All serial numbers
E-2 and F-2 All serial numbers
J3C-40, J3C-50, J3C-50S, (Army L-4, L-4B, All serial numbers
L-4H, and L-4J), J3C-65 (Navy NE-1 and
NE-2), J3C-65S J3F-50, J3F-50S, J3F-60,
J3F-60S, J3F-65 (Army L-4D), J3F-65S,
J3L, J3L-S, J3L-65 (Army L-4C), and J3L-65S
J4, J4A, J4A-S, and J4E (Army L-4E) 4-401 through 4-1649
J5A (Army L-4F), J5A-80, J5B, (Army L-4G), All serial numbers
J5C, L-14, AE-1, and HE-1
PA-11 and PA-11S 11-1 through 11-1678
PA-12 and PA-12S 12-1 through 12-4036
PA-14 14-1 through 14-523
PA-15 15-1 through 15-388
PA-16 and PA-16S 16-1 through 16-736
PA-17 17-1 through 17-215
PA-18, PA-18S, PA-18 "105" (Special), 18-1 through 18-8309025,
PA-18S "105" (Special) PA-18A, PA-18 "125", 189001 through 1809032,
(Army L-21A), PA-18S "125", PA-18AS "125", and 1809034 through
PA-18 "135" (Army L-21B), PA-18A "135", 1809040
PA-18S "135", PA-18AS "135", PA-18 "150",
PA-18A "150", PA-18S "150", PA-18AS "150",
PA-18A (Restricted),PA-18A "135" (Restricted),
and PA-18A "150" (Restricted)
PA-19 (Army L-18C), and PA-19S 19-1, 19-2, and 19-3
PA-20, PA-20S, PA-20 "115", PA-20S "115", 20-1 through 20-1121
PA-20 "135", and PA-20S "135"
PA-22, PA-22-108, PA-22-135, PA-22S-135, 22-1 through 22-9848
PA-22-150, PA-22S-150, PA-22-160, and
PA-22S-160
PA-25, PA-25-235, and PA-25-260 25-1 through 25-8156024
NOTE 1: This AD applies to each airplane identified in
the preceding applicability provision, regardless of whether
it has been modified, altered, or repaired in the area
subject to the requirements of this AD. For airplanes that
have been modified, altered, or repaired so that the
performance of the requirements of this AD is affected, the
owner/operator must request approval for an alternative
method of compliance in accordance with paragraph (f) of
this AD. The request should include an assessment of the
effect of the modification, alteration, or repair on the
unsafe condition addressed by this AD; and, if the unsafe
condition has not been eliminated, the request should
include specific proposed actions to address it.
Compliance: Required as indicated in the body of this
AD, unless already accomplished.
To prevent in-flight separation of the wing from the
airplane caused by corroded wing lift struts or cracked wing
lift strut forks, which could result in loss of control of
the airplane, accomplish the following:
NOTE 2: The paragraph structure of this AD is as follows:
Level 1: (a), (b), (c), etc.
Level 2: (1), (2), (3), etc.
Level 3: (i), (ii), (iii), etc.
Level 4: (A), (B), (C), etc.
Level 2, Level 3, and Level 4 structures are designations of
the Level 1 paragraph they immediately follow.
(a) For all affected airplane models, within 1 calendar
month after the effective date of this AD or within 24
calendar months after the last inspection accomplished in
accordance with AD 93-10-06 (superseded by this action),
whichever occurs later, remove the wing lift struts in
accordance with Piper Service Bulletin (SB) No. 528D, dated
October 19, 1990, or Piper SB No. 910A, dated October 10,
1989, as applicable, and accomplish one of the following
(the actions in either paragraph (a)(1), (a)(2), (a)(3),
(a)(4), or (a)(5); including subparagraphs, of this AD):
(1) Inspect the wing lift struts for corrosion
in accordance with the "Instructions" section in Part I of
either Piper SB No. 528D, dated October 19, 1990, or Piper
SB No. 910A, dated October 10, 1989, as applicable.
(i) If no perceptible dents (as defined
in the above SB's) are found in the wing lift strut and no
corrosion is externally visible, prior to further flight,
apply corrosion inhibitor to each strut in accordance with
whichever of the above SB's that is applicable. Reinspect
the lift struts at intervals not to exceed 24 calendar
months and accomplish any of the requirements of paragraph
(a) of this AD, including all subparagraphs.
(ii) If a perceptible dent (as defined
in the above SB's) is found in the wing lift strut or external
corrosion is found, prior to further flight, accomplish one
of the installations (and subsequent actions presented in
each paragraph) specified in paragraphs (a)(3), (a)(4), or
(a)(5) of this AD.
(2) Inspect the wing lift struts for corrosion in
accordance with the Appendix to this AD. The inspection
procedures in this Appendix must be accomplished by a Level
2 inspector certified using the guidelines established by
the American Society for Non-destructive Testing, or MIL-
STD-410.
(i) If no corrosion is found that is
externally visible and all requirements in the Appendix to this
AD are met, prior to further flight, apply corrosion inhibitor to
each strut in accordance with whichever of the above SB's
that is applicable. Reinspect the lift struts at intervals
not to exceed 24 calendar months and accomplish any of the
requirements of paragraph (a) of this AD, including all
subparagraphs.
(ii) If external corrosion is found or if
any of the requirements in the Appendix of this AD are not met,
prior to further flight, accomplish one of the installations
(and subsequent actions presented in each paragraph)
specified in paragraphs (a)(3), (a)(4), or (a)(5) of this
AD.
(3) Install original equipment manufacturer (OEM)
part number wing struts (or FAA-approved equivalent part
numbers) that have been inspected in accordance with the
specifications presented in either paragraph (a)(1) or
(a)(2) of this AD, and are found to be airworthy according
to the inspection requirements included in these paragraphs.
Thereafter, inspect these wing lift struts at intervals not
to exceed 24 calendar months in accordance with the
specifications presented in either paragraph (a)(1) or
(a)(2) of this AD.
(4) Install new sealed wing lift strut assemblies,
part numbers as specified in Piper SB No. 528D and Piper SB
No. 910A (or FAA-approved equivalent part numbers) on each
wing as specified in the Instructions section in Part II of
the above-referenced SB's. These sealed wing lift strut
assemblies also include the wing lift strut forks.
Installation of these assemblies constitute terminating
action for the inspection requirements of both paragraphs
(a) and (b) of this AD.
(5) Install F. Atlee Dodge wing lift strut
assemblies in accordance with F. Atlee Dodge Installation
Instructions No. 3233-I for Modified Piper Wing Lift Struts
(Supplemental Type Certificate (STC) SA4635NM), dated
February 1, 1991. Thereafter, inspect these wing lift
struts at intervals not to exceed 60 calendar months in
accordance with the specifications presented in paragraph
(a)(1) or (a)(2) of this AD.
(b) For all affected airplane models, except for Models
PA-25, PA-25-235, and PA-25-260, within the next 100 hours
time-in-service (TIS) after the effective date of this AD or
within 500 hours TIS after the last inspection accomplished
in accordance with AD 93-10-06 (superseded by this action),
whichever occurs later, remove the wing lift strut forks,
and accomplish one of the following (the actions in either
paragraph (b)(1), (b)(2), (b)(3), (b)(4), or (b)(5);
including subparagraphs, of this AD):
(1) Inspect the wing lift strut forks using FAA-
approved magnetic particle procedures.
(i) If no cracks are found, reinspect at
intervals not to exceed 500 hours TIS provided that the
replacement requirements of paragraphs (b)(1)(ii)(B) and
(b)(1)(ii)(C) of this AD have been met.
(ii) Replace the wing lift strut forks at
whichever of the following is applicable:
(A) If cracks are found on any wing
lift strut fork: Prior to further flight;
(B) If the airplane is equipped with
floats or has been equipped with floats within the last 2,000 hours
TIS and no cracks are found during the above inspections:
Upon accumulating 1,000 hours TIS on the wing lift strut
forks or within the next 100 hours TIS, whichever occurs
later; or
(C) If the airplane has not been
equipped with floats within the last 2,000 hours TIS and no cracks
are found during the above inspections: Upon accumulating 2,000
hours TIS on the wing lift strut forks or within the next
100 hours TIS, whichever occurs later.
(iii) Replacement parts shall be of the
same part numbers of the existing part (or FAA-approved equivalent
part numbers) and shall be manufactured with rolled threads.
Lift strut forks manufactured with machined (cut) threads
shall not be utilized.
(iv) The 500-hour TIS interval repetitive
inspections are still required when the above replacements
are accomplished.
(2) Install new OEM part number wing lift strut
forks (or FAA-approved equivalent part numbers). Reinspect
and replace these wing lift strut forks at the intervals
specified in paragraphs (b)(1)(i), (b)(1)(ii), (b)(1)(iii),
and (b)(1)(iv), including all subparagraphs, of this AD.
(3) Install new sealed wing lift strut assemblies,
part numbers as specified in Piper SB No. 528D and Piper SB
No. 910A (or FAA-approved equivalent part numbers) on each
wing, as specified in the Instructions section in Part II of
the above-referenced SB's.
(i) This installation may have "already
been accomplished" through the actions specified in paragraph
(a)(4) of this AD.
(ii) No repetitive inspections are required
after installing these sealed wing lift strut assemblies.
(4) Install Jensen Aircraft wing lift strut fork
assemblies as specified in the STC's presented in the
paragraphs that follow, as applicable, in accordance with
Jensen Aircraft Installation Instructions for Modified Lift
Strut Fittings, which incorporates the following pages:
Pages Revision Level Date
1 and 5 Original Issue July 15, 1983
2, 4, and 6 Revision No. 1 March 30, 1984
a and 3 Revision No. 2 April 20, 1984
No repetitive inspections are required after installing
these Jensen Aircraft wing lift strut fork assemblies;
however, repetitive inspections of the lift strut are
required as specified in paragraph (a)(1), (a)(2), or (a)(3)
of this AD:
(i) For Models PA-12 and PA-12S airplanes:
STC SA1583NM;
(ii) For Model PA-14 airplanes:
STC SA1584NM;
(iii) For the Models PA-16 and PA-16S
airplanes: STC SA1590NM;
(iv) For the Models PA-18, PA-18S,
189001 PA-18 "105" (Special), PA-18S "105" (Special), PA-18A,
PA-18 "125" (Army L-21A), PA-18S "125", PA-18AS "125", PA-18 "135"
(Army L-21B), PA-18A "135", PA-18S "135", PA-18S "135", PA-18AS
"135", PA-18 "150", PA-18A "150", PA-18S "150", PA-18AS
"150", PA-18A (Restricted), PA-18A "135" (Restricted), and
PA-18A "150" (Restricted) airplanes: STC SA1585NM;
(v) For the Models PA-20, PA-20S,
PA-20 "115", PA-20S "115", PA-20 "135", and PA-20S "135"
airplanes: STC SA1586NM; and
(vi) For the Model PA-22 airplanes:
STC SA1587NM.
(5) Install F. Atlee Dodge wing lift strut
assemblies in accordance with F. Atlee Dodge Installation
Instructions No. 3233-I for Modified Piper Wing Lift Struts
(STC SA4635NM), dated February 1, 1991.
(i) No repetitive inspections of the wing
lift strut forks are required when these assemblies are
installed.
(ii) This installation may have "already
been accomplished" through the actions specified in paragraph
(a)(5) of this AD.
(c) If holes are drilled, in either one of the
scenarios presented in paragraphs (c)(1) and (c)(2) of this
AD, to attach cuffs, door clips, or other hardware, inspect
the wing lift struts at intervals not to exceed 24 calendar
months using the procedures specified in paragraphs (a)(1)
and (a)(2), including all subparagraphs, of this AD:
(1) Wing lift strut assemblies installed in
accordance with (a)(4) or (b)(3) of this AD; or
(2) F. Atlee Dodge wing lift strut assemblies
installed in accordance with paragraph (a)(5) or (b)(5) of
this AD.
(d) For all affected airplane models, within 1 calendar
month after the effective date of this AD or within 24
calendar months after the last inspection accomplished in
accordance with AD 93-10-06 (superseded by this action),
whichever occurs later, and thereafter prior to further
flight after the installation of any lift strut assembly,
accomplish one of the following:
(1) Install "NO STEP" decal, Piper part number
(P/N) 80944-02, on each wing lift strut approximately 6 inches
from the bottom of the struts in a way that the letters can
be read when entering and exiting the aircraft; or
(2) Paint the statement "NO STEP" approximately 6
inches from the bottom of the struts in a way that the
letters can be read when entering and exiting the aircraft.
Use a minimum of 1-inch letters using a color that contrasts
with the color of the airplane.
(e) Special flight permits may be issued in accordance
with sections 21.197 and 21.199 of the Federal Aviation
Regulations (14 CFR 21.197 and 21.199) to operate the
airplane to a location where the requirements of this AD can
be accomplished.
(f) An alternative method of compliance or adjustment
of the initial or repetitive compliance times that provides
an equivalent level of safety may be approved by the
Manager, Atlanta Aircraft Certification Office (ACO),
One Crown Center, 1895 Phoenix Boulevard, suite 450,
Atlanta, Georgia 30349.
(1) The request shall be forwarded through an
appropriate FAA Maintenance Inspector, who may add comments
and then send it to the Manager, Atlanta ACO.
(2) Alternative methods of compliance approved in
accordance with AD 93-10-06, Amendment 39-8536, are
considered approved as alternative methods of compliance for
this AD.
NOTE 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may
be obtained from the Atlanta Aircraft Certification Office.
(g) The inspections required by this AD shall be done
in accordance with Piper Service Bulletin No. 528D, dated
October 19, 1990, and Piper Service Bulletin No. 910A, dated
October 10, 1989. The installation required by this AD
shall be done in accordance with F. Atlee Dodge Installation
Instructions No. 3233-I for Modified Piper Wing Lift Struts
(Supplemental Type Certificate (STC) SA4635NM), dated
February 1, 1991, and Jensen Aircraft Installation
Instructions for Modified Lift Strut Fittings, which
incorporates the following pages:
Pages Revision Level Date
1 and 5 Original Issue July 15, 1983
2, 4, and 6 Revision No. 1 March 30, 1984
a and 3 Revision No. 2 April 20, 1984
This incorporation by reference was approved by the Director
of the Federal Register in accordance with 5 U.S.C. 552(a)
and 1 CFR part 51. The service bulletins referenced in this
AD may be obtained from The New Piper Aircraft, Inc.,
Customer Services, 2926 Piper Drive, Vero Beach, Florida
32960. Copies of the instructions to the Jensen Aircraft
STC's may be obtained from Jensen Aircraft, 9225 County Road
140, Salida, Colorado 81201. Copies of the instructions to
the F. Atlee Dodge STC may be obtained from F. Atlee Dodge,
Aircraft Services, Inc., P.O. Box 190409, Anchorage, Alaska
99519-0409. Copies may be inspected at the FAA, Central
Region, Office of the Regional Counsel, Room 1558, 601 E.
12th Street, Kansas City, Missouri, or at the Office of the
Federal Register, 800 North Capitol Street, NW, suite 700,
Washington, DC.
(h) This amendment supersedes AD 93-10-06, Amendment
39-8536.
(i) This amendment becomes effective on February 8,
1999.
FOR FURTHER INFORMATION CONTACT:
William O. Herderich, Aerospace Engineer, FAA, Atlanta
Certification Office, One Crown Center,
1895 Phoenix Boulevard, suite 450, Atlanta, Georgia 30349;
telephone: (770) 703-6084; facsimile: (770) 703-6097.
**************************************************************
APPENDIX TO AD 99-01-05; AMENDMENT 39-10972;
DOCKET NO. 96-CE-72-AD
PROCEDURES AND REQUIREMENTS
FOR ULTRASONIC INSPECTION OF PIPER WING LIFT STRUTS
Equipment Requirements
1. A portable ultrasonic thickness gauge or flaw detector
with echo-to-echo digital thickness readout capable of
reading to 0.001-inch and an A-trace waveform display will
be needed to accomplish this inspection.
2. An ultrasonic probe with the following specifications
will be needed to accomplish this inspection: 10 MHz (or
higher), 0.283-inch (or smaller) diameter dual element or
delay line transducer designed for thickness gauging. The
transducer and ultrasonic system shall be capable of
accurately measuring the thickness of AISI 4340 steel down
to 0.020-inch. An accuracy of +/- 0.002-inch throughout a
0.020-inch to 0.050-inch thickness range while calibrating
shall be the criteria for acceptance.
3. Either a precision machined step wedge made of 4340
steel (or similar steel with equivalent sound velocity) or
at least three shim samples of same material will be needed
to accomplish this inspection. One thickness of the step
wedge or shim shall be less than or equal to 0.020-inch, one
shall be greater than or equal to 0.050-inch, and at least
one other step or shim shall be between these two values.
4. Glycerin, light oil, or similar non-water based
ultrasonic couplants are recommended in the setup and
inspection procedures. Water-based couplants, containing
appropriate corrosion inhibitors, may be utilized, provided
they are removed from both the reference standards and the
test item after the inspection procedure is completed and
adequate corrosion prevention steps are then taken to
protect these items.
NOTE: Couplant is defined as "a substance used between
the face of the transducer and test surface to improve
transmission of ultrasonic energy across the
transducer/strut interface."
NOTE: If surface roughness due to paint loss or
corrosion is present, the surface should be sanded or
polished smooth before testing to assure a consistent and
smooth surface for making contact with the transducer. Care
shall be taken to remove a minimal amount of structural
material. Paint repairs may be necessary after the
inspection to prevent further corrosion damage from
occurring. Removal of surface irregularities will enhance
the accuracy of the inspection technique.
Instrument Setup
1. Set up the ultrasonic equipment for thickness
measurements as specified in the instrument's user's manual.
Because of the variety of equipment available to perform
ultrasonic thickness measurements, some modification to this
general setup procedure may be necessary. However, the
tolerance requirement of step 13 and the record keeping
requirement of step 14, must be satisfied.
2. If battery power will be employed, check to see that
the battery has been properly charged. The testing will
take approximately two hours. Screen brightness and
contrast should be set to match environmental conditions.
3. Verify that the instrument is set for the type of
transducer being used, i.e. single or dual element, and that
the frequency setting is compatible with the transducer.
4. If a removable delay line is used, remove it and place
a drop of couplant between the transducer face and the delay
line to assure good transmission of ultrasonic energy.
Reassemble the delay line transducer and continue.
5. Program a velocity of 0.231-inch/microsecond into the
ultrasonic unit unless an alternative instrument calibration
procedure is used to set the sound velocity.
6. Obtain a step wedge or steel shims per item 3 of the
Equipment Requirements. Place the probe on the thickest
sample using couplant. Rotate the transducer slightly back
and forth to "ring" the transducer to the sample. Adjust
the delay and range settings to arrive at an A-trace signal
display with the first backwall echo from the steel near the
left side of the screen and the second backwall echo near
the right of the screen. Note that when a single element
transducer is used, the initial pulse and the delay
line/steel interface will be off of the screen to the left.
Adjust the gain to place the amplitude of the first backwall
signal at approximately 80% screen height on the A-trace.
7. "Ring" the transducer on the thinnest step or shim
using couplant. Select positive half-wave rectified,
negative half-wave rectified, or filtered signal display to
obtain the cleanest signal. Adjust the pulse voltage, pulse
width, and damping to obtain the best signal resolution.
These settings can vary from one transducer to another and
are also user dependent.
8. Enable the thickness gate, and adjust the gate so
that it starts at the first backwall echo and ends at the
second backwall echo. (Measuring between the first and
second backwall echoes will produce a measurement of the
steel thickness that is not affected by the paint layer on
the strut). If instability of the gate trigger occurs,
adjust the gain, gate level, and/or damping to stabilize the
thickness reading.
9. Check the digital display reading and if it does
not agree with the known thickness of the thinnest thickness,
follow your instrument's calibration recommendations to
produce the correct thickness reading. When a single
element transducer is used this will usually involve
adjusting the fine delay setting.
10. Place the transducer on the thickest step of shim
using couplant. Adjust the thickness gate width so that the
gate is triggered by the second backwall reflection of the
thick section. If the digital display does not agree with
the thickest thickness, follow your instruments calibration
recommendations to produce the correct thickness reading. A
slight adjustment in the velocity may be necessary to get
both the thinnest and the thickest reading correct.
Document the changed velocity value.
11. Place couplant on an area of the lift strut which
is thought to be free of corrosion and "ring" the transducer
to surface. Minor adjustments to the signal and gate
settings may be required to account for coupling
improvements resulting from the paint layer. The thickness
gate level should be set just high enough so as not to be
triggered by irrelevant signal noise. An area on the upper
surface of the lift strut above the inspection area would be
a good location to complete this step and should produce a
thickness reading between 0.034-inch and 0.041-inch.
12. Repeat steps 8, 9, 10, and 11 until both thick and
thin shim measurements are within tolerance and the lift
strut measurement is reasonable and steady.
13. Verify that the thickness value shown in the
digital display is within +/- 0.002-inch of the correct
value for each of the three or more steps of the setup wedge
or shims. Make no further adjustments to the instrument
settings.
14. Record the ultrasonic versus actual thickness of
all wedge steps or steel shims available as a record of
setup.
Inspection Procedure
1. Clean the lower 18 inches of the wing lift struts
using a cleaner that will remove all dirt and grease. Dirt
and grease will adversely affect the accuracy of the
inspection technique. Light sanding or polishing may also
be required to reduce surface roughness as noted in the
Equipment Requirements section.
2. Using a flexible ruler, draw a 1/4-inch grid on the
surface of the first 11 inches from the lower end of the
strut as shown in Piper Service Bulletin No. 528D or 910A,
as applicable. This can be done using a soft (#2) pencil
and should be done on both faces of the strut. As an
alternative to drawing a complete grid, make two rows of
marks spaced every 1/4-inch across the width of the strut.
One row of marks should be about 11 inches from the lower
end of the strut, and the second row should be several
inches away where the strut starts to narrow. Lay the
flexible ruler between respective tick marks of the two rows
and use tape or a rubber band to keep the ruler in place.
See Figure 1.
ILLUSTRATION (Figure 1)
3. Apply a generous amount of couplant inside each of the
square areas or along the edge of the ruler. Re-application
of couplant may be necessary.
4. Place the transducer inside the first square area of
the drawn grid or at the first 1/4-inch mark on the ruler
and "ring" the transducer to the strut. When using a dual
element transducer, be very careful to record the thickness
value with the axis of the transducer elements perpendicular
to any curvature in the strut. If this is not done, loss of
signal or inaccurate readings can result.
5. Take readings inside each square on the grid or at
1/4-inch increments along the ruler and record the results.
When taking a thickness reading, rotate the transducer
slightly back and forth and experiment with the angle of
contact to produce the lowest thickness reading possible.
Pay close attention to the A-scan display to assure that the
thickness gate is triggering off of maximized backwall
echoes.
NOTE: A reading shall not exceed .041-inch. If a
reading exceeds .041-inch, repeat steps 13 and 14 of the
Instrument Setup section before proceeding further.
6. If the A-trace is unsteady or the thickness reading is
clearly wrong, adjust the signal gain and/or gate setting to
obtain reasonable and steady readings. If any instrument
setting is adjusted, repeat steps 13 and 14 of the
Instrument Setup section before proceeding further.
7. In areas where obstructions are present, take a data
point as close to the correct area as possible.
NOTE: The strut wall contains a fabrication bead at
approximately 40% of the strut chord. The bead may
interfere with accurate measurements in that specific
location.
8. A measurement of 0.024-inch or less shall require
replacement of the strut prior to further flight
9. If at any time during testing an area is encountered
where a valid thickness measurement cannot be obtained due
to a loss of signal strength or quality, the area shall be
considered suspect. These areas may have a remaining wall
thickness of less than 0.020-inch, which is below the range
of this setup, or they may have small areas of localized
corrosion or pitting present. The latter case will result
in a reduction in signal strength due to the sound being
scattered from the rough surface and may result in a signal
that includes echoes from the pits as well as the backwall.
The suspect area(s) shall be tested with a Maule "Fabric
Tester" as specified in Piper Service Bulletin No. 528D or
910A.
10. Record the lift strut inspection in the aircraft
log book.
Perhaps this is one of those can of worms? (hard to sort out). 
R. JOHNSON
Registered User
DODGEVILLE WI
Punch testing the old struts is a pain in the ass. A couple of months ago I was helping our IA w/ an "owner assisted" annual on our J-3 and it took me all afternoon to punch them. Finally when I was almost done w/ the fourth strut but slipped off and the damn maule tester came flying apart :x for the third time my IA just shook his head and told me to stop.
Does anyone know if Jensen Aircraft will still seal the old struts? I used to see them advertised in Cub Clues.
Ryan
Does anyone know if Jensen Aircraft will still seal the old struts? I used to see them advertised in Cub Clues.
Ryan
cubpilot2
SPONSOR
Anchorage Alaska
TJ
I'm the one responsible for the "confusion" on this, but perhaps you can see how it can be a bit "unclear".
In my desire to get an "authoritative answer" I tossed this one at my local FAA rep. and asked him to decipher it. After looking at it for a long time in the printed version that I had; and then compared it to his computer version there was a difference in the way it printed the thing. On his it was clear that (B) is contained as part of (b) or in other words (B) appears as an indented paragraph below (b). It did not do this in the version I was reading from. (similar to what Steve pasted in this post) To make the long story short he finally said to consider the larger forks "lifetime". I had also called Univair and only talked to a sales guy who after talking to others said the same thing.
Better to "sort these things out for certain" then to think we know what it says and then later learn otherwise.
Only 5 more days until Santa brings my 31" radials. (I hope/wish)
Hope he isn't held up due to doing strut fork replacements on the old sled.....
Merry Christmas to All
I'm the one responsible for the "confusion" on this, but perhaps you can see how it can be a bit "unclear".
In my desire to get an "authoritative answer" I tossed this one at my local FAA rep. and asked him to decipher it. After looking at it for a long time in the printed version that I had; and then compared it to his computer version there was a difference in the way it printed the thing. On his it was clear that (B) is contained as part of (b) or in other words (B) appears as an indented paragraph below (b). It did not do this in the version I was reading from. (similar to what Steve pasted in this post) To make the long story short he finally said to consider the larger forks "lifetime". I had also called Univair and only talked to a sales guy who after talking to others said the same thing.
Better to "sort these things out for certain" then to think we know what it says and then later learn otherwise.
Only 5 more days until Santa brings my 31" radials. (I hope/wish)
Hope he isn't held up due to doing strut fork replacements on the old sled.....
Merry Christmas to All
Steve Pierce
BENEFACTOR
Graham, TX
I read this "sealed wing strut assemblies" as the sealed strut and larger fork. Thus eliminating the recurring AD. At least i hope so or I'll be in deep wooster.
Steve Pierce
BENEFACTOR
Graham, TX
TJ, Go have a beer. Too much work for a Friday night.
SuperCub MD
Registered User
Collins, Wisconsin
Ever run across "sealed lifetime" struts that Wag sells for J3's? They are sealed, but still have a small fork. I researched it, and concluded that even with the small fork, they are lifetime on these struts on a J3. Can't remember how I came to this conclusion, but do remember it was a paperwork nightmare. If you get sealed struts for a J3, get them from Univair so that you get the big forks.
