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Pa-12 0-235 prop mount question

TennesseeAndy

Registered User
Finishing up a rebuild of a ‘46 cruiser that was bought disassembled. It looks like there is an afterMarket prop spacer to accommodate the metal prop. There are 4 1/2” bolts with brushings for the prop to slide onto. But the bolts are undrilled; is this correct? Is the prop just held on with locknuts? If not will someone please enlighten me as to the correct hardware. Thanks in advance. Andy
 
What prop are you installing? The flange on the engine should have threaded bushings installed. Foe Sensenich props, there are specific bolts called out for the installation, and they are all drilled for safety wire. The prop application list is here Application_Guides_Aluminum_Propeller_Applications_1349891787.pdf (sensenich.com) and the bolt listing is on the last page. Here is the bolt price list 2019-Bolts.pdf (sensenich.com)



Thanks... The engine flange does in fact have threaded brushings but that is what the spacer is bolted onto- and those bolts are drilled for wire. The prop bolts are facing outward, coming through the spacer, with the heads of the bolts sandwiched between the engine flange and the spacer. The prop then slides onto the bolts and is tightened with presumably castle nuts and pins. I imagine this setup allowed the original spinner to be used with an aluminum prop. Does any of this ring a bell? The guy at Sensenich was scratching his head. I’m looking for someone who has seen this before. Thanks again - Andy
 
When I bought my -12 in 1974 it had O-235, metal prop, and a rather stubby spinner (not skull-cap). The prop bolted directly to the crank flange, no spacer. I assume was all original, but can't be certain..
 
I have seen this spacer on a PA-12. I can not tell you why it is there, but I have seen several with it. The prop bolts are retained from rotation due to their heads being captured behind the spacer. Thus the uses of elastic stop nuts would be acceptable.
 
The prop spacer is not correct for a PA 12, the prop should bolt directly to the crank. However the hub thickness ( Series M) prop that is unique to 0235 takes bolts that are approximately 3/4" shorter than the later props for 0290/0320's. So lots of folks have tryed to try a 0235 prop on an 0290 and found out their prop bolts were way to long............. The prop hub on the original 0235 props is much thinner...... Not sure WHY you have that spacer but you don't need it.
E
 
There was an adapter for the O-235 crank flange adapting a McCauley prop to that engine. The correct Sensenich prop does not need that adapter. Reference the Typer Certificate Data Sheet for airframe, engine and prop.
 
Good info Steve, I was wondering if it may have been used to install the "Aeromatic" prop on them???
 
FWIW Sensenich makes a "spacer prop", which was the listed prop on the STC for my C150/150 conversion.
74DM6-S5-54, the "S5" indicating a 1-1/4" (as I recall) spacer.
The spacer is dowelled to the prop via two extra holes drilled into the prop 180 degrees apart,
and the six prop bolts go through the whole works into the crankshaft flange.
 
There was an adapter for the O-235 crank flange adapting a McCauley prop to that engine. The correct Sensenich prop does not need that adapter. Reference the Typer Certificate Data Sheet for airframe, engine and prop.

Our first PA-12 had this adapter with a McCauley 7142 climb prop, referred to as McCauley Metal Klip-Tip. I liked it a lot, so if you have that set up, just confirm the correct install IAW the TCDS. Ask a prop shop if in doubt, but make sure they know what they're talking about.:roll:
 
FWIW Sensenich makes a "spacer prop", which was the listed prop on the STC for my C150/150 conversion.
74DM6-S5-54, the "S5" indicating a 1-1/4" (as I recall) spacer.
The spacer is dowelled to the prop via two extra holes drilled into the prop 180 degrees apart,
and the six prop bolts go through the whole works into the crankshaft flange.
This is a different type of spacer.
 
I have a -12 with the McCauley adapter but the paperwork is in AK. I recall the adapter to flange bolts were specified in the paperwork and were not common bolts. They are drilled head NAS bolts if I remember right, safetied out and around the adapter with the prop bolt heads captured in the adapter bosses with lock nuts. I ran a skull cap spinner and it was not clear if a spinner bulkhead was approved between the adapter and prop for a full spinner. Been a long time since I installed it.
Ken
 
My J5C with a 0235c using a McCulley 72x38 had one…saw one on my buddys with a 0235c1 as well…
 
There may have been other propellers that Piper made available on the original airplanes, but I believe the buyer's choices were either the standard wood propeller of various pitches or the two-position, adjustable inflight Sensenich "Sky Blade" propeller. This propeller had wood core blades and a mechanical pitch change mechanism. To my knowledge, a metal propeller was not available from the factory.

There were a lot of PA-12s around in the 40s and 50s with Aeromatic propellers, but I think they were aftermarket installs done with an S.T.C.

Clyde Smith needs to weigh in on this one.
 
Here are the 7 propellers which are approved on the PA-12 TC. A-780 The Aeromatic is #2.

Propellers and Propeller Accessories
1. Propeller - Sensenich 74FE44, 74FE54, or any other fixed pitch wood propeller which +11 lbs. (-62)is eligible for the engine power and speed and which meets the following limits:(a) With O-235-C or O-235-C1 engine - landplane and skiplane: Static rpm at max. permissible throttle setting:Not over 2300, not under 1900. No additional tolerance permitted. Diameter: Not over 76 inches, not under 72 inches.(b) With O-235-C or O-235-C1 engine - seaplane (see Item 103 for manual revisionand seaplane equipment required with O-235-C1 engine):Static rpm at max. permissible throttle setting:Not over 2400, not under 2350.No additional tolerance permitted.Diameter: Not over 76 in., not under 72 in.

*2. Propeller - Koppers Aeromatic F200/00-74E +21 lbs. (-62)Diameter: Not over 74 inches, not under 72.5 inches.Low pitch setting at 24 inch station: 11°Static rpm limits at max. permissible throttle setting(No additional tolerance permitted):(a) With O-235-C engine - landplane, skiplane and seaplane (Parts List Assembly No. 4292):Not over 2550, not under 2500.(b) With O-235-C1 engine - landplane, skiplane and seaplane (Parts List Assembly No. 4292A dated April 9, 1948):Not over 2750, not under 2650. (See Item 103 for required seaplane equipment)The Airplane Flight Manual must reflect this installation under "Limitations" with respect to assembly parts list number,low pitch settings, diameter and static rpm limits and must include the following statement: "Installation and operation mustbe accomplished in accordance with Kopper's Installation Procedure and Operating Limitations dated May 4, 1948 (Item2(a)), or March 10, 1948, revised September 27, 1948 (Item 2(b))."Under the "Performance" section the following statement must be included:"Performance with (_________) engine and the Kopper's Aeromatic Propeller has been demonstrated to equal or exceedthat shown herein for the O-235-C engine and fixed pitch wood propeller. Performance at altitude may be improved byincreasing the flight rpm in accordance with paragraph D(3) of the approved 'Installation Procedure and OperatingLimitations.' "Paragraph E of the "Installation Procedure and Operating Limitations" should be revised as follows:"Counterweights must be added after landing at a field of elevation 2000 feet or more below that at which thecounterweights were last set. This adjustment is required for optimum performance and to avoid exceeding rated rpm atfull throttle during take-off and climb." This revision to paragraph E will be incorporated in the next revision of"Installation Procedure and Operating Limitations" by the Kopper's Propeller Company.

*3. Propeller - Sensenich, two-position controllable, hubs C-2FM-3, C-2FM-4, +27 lbs. (-62)or C-2FM-5 with PC-276A6 bladesDiameter: Not over 76 inches, not under 74 inches.continuedA-780 Page 4 of 7Propeller and Propeller Accessories, continued *3. Propeller – Sensenich, two-position controllable, hubs C-2FM-3, C-2FM-4, continuedBlade pitch settings at 3/4 radius (28.5 in. station): Low High(a) For landplane and skiplane with O-235-C engine 8½° 13°(b) For landplane and skiplane with O-235-C1 engine 7½° 13°(c) For seaplane with O-235-C1 engine 7° 12° (See Item 103 for required equipment).When this propeller is installed, the Airplane Flight Manual must reflect the installation under "Limitations" withrespect to propeller identification and limits. The "Performance" section must include the following statement:"Performance with the (____________) engine and Sensenich Two-Position Propeller has been demonstrated to equalor exceed that shown herein for the O-235-C engine and fixed pitch wood propeller." For seaplane with O-235-C1engine, the above statement must be amended to include the following statement: "Climb performance shown may be realizedafter the expiration of the one-minute take-off power time limit by operating in high pitch, full throttle only."

*4. Propeller - fixed pitch metal, McCauley 1A110 +29 lbs. (-62)Landplane and skiplane with O-235-C1 engine only.Diameter: Not over 76 inches, not under 74 inches.Static rpm at max. permissible throttle setting:Not over 2400, not under 2150.No additional tolerance permitted.When this propeller is installed, the Airplane Flight Manual must reflect the installation under "Limitations" withrespect to propeller identification and limits. The "Performance" section must include the following statement:"Performance with O-235-C1 engine and McCauley 1A110 propeller has been demonstrated to equal or exceed thatshown herein for the O-235-C engine and fixed pitch wood propeller."

*5. Propeller - controllable, Beech R003 which includes R003-342 adapter, +21 lbs. (-62)R003-100 hub, R003-225-75 blades, manual control, and spinner(Required equipment with this prop.).Landplane and skiplane with O-235-C engine only.Diameter: Not over 75 inches, not under 73.5 inches.Blade setting at 3/4 radius (28.5 in. station): Low High13.5° 18.3°When this propeller is installed, the Airplane Flight Manual must reflect the installation under "Limitations" withrespect to propeller identification and limits. The "Performance" section must include the following statement:“Performance with O-235-C engine and Beech R003 propeller has been demonstrated to equal or exceed that shownherein for the O-235-C engine and fixed pitch wood propeller."

*6. Propeller - fixed pitch metal, McCauley 1C90-LM +21 lbs. (-62)Diameter: Not over 72 inches, not under 70.5 inches.Static rpm at max. permissible throttle setting (No additional tolerance permitted):(a) Landplane and skiplane with O-235-C or O-235-C1 engine -Not over 2500, not under 2100.(b) Seaplane with O-235-C or O-235-C1 engine -(See Item 103 for required equipment with O-235-C1 engine)Not over 2500, not under 2350.When this propeller is installed, the Airplane Flight Manual must reflect the installation under "Limitations" with respectto propeller identification and limits. The "Performance" section must include the following statement: "Performancewith the (____________) engine and McCauley 1C90-LM Propeller has been demonstrated to equal or exceed thatshown herein for the O-235-C engine and fixed pitch wood propeller."*7. Propeller - fixed pitch metal, Sensenich M76AM-2 +24 lbs. (-62)Diameter: Not over 74 inches, not under 72.5 inches.With engines O-235-C engine and O-235-C1 only.Static rpm at max. permissible throttle setting (No additional tolerance permitted):(a) Landplane and skiplane only -,Not over 2425, not under 2150.continuedPage 5 of 7 A-780Propellers and Propeller Accessories, continued

*7. Propeller – fixed pitch metal, Sensenich M76AM-2, continued(b) Seaplane only (See Item 103 for required equipment with O-235-C1) -Not over 2425, not under 2325.When this propeller is installed, the Airplane Flight Manual must be revised to reflect this installation under"Limitations" with respect to propeller identification and limits. The "Performance" section must include the followingstatement: "Performance with the O-235-C (or O-235-C1) engine and Sensenich M76AM-2 propeller has been demonstrated to equal or exceed that shown herein for the O-235-C engine and fixed pitch wood propeller."
 
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