It seems to me whether you have all the “gizmos” or not is irrelevant. It’s how you use them. The pilot always has, and always will be the biggest variable in aviation. Watch any of the “Air Disaster” type series on TV. From new pilots to seasoned professional, most accidents have a large human factors component. You don’t need to be a professional pilot to develop standard procedures that may help you avoid some of the pitfalls of flying. Always announce if you have a radio, always fly a pattern, always do a 360 to scan for traffic before departure. No guarantees, but cheap insurance. You’ll never have to explain why you did these things, but you may have to explain why you didn’t.
Oops, darn it...
- Thread starter Anne
- Start date
Farmboy
MEMBER
Middlebury, VT
Student and inexperienced pilots are subjected to what ever pilot influence is within earshot. I say this because on one of my many trips as a young pilot I announced x miles out to an airport in MA. Then I announced entering downwind.
And then someone presumably at the airport keyed up and said “we don’t make blind announcements at xyz airport”.
I wondered if I had done something wrong, or how anyone knew where anyone else was, but either way I shut up and never said another word.
Today that would be a different response.
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And then someone presumably at the airport keyed up and said “we don’t make blind announcements at xyz airport”.
I wondered if I had done something wrong, or how anyone knew where anyone else was, but either way I shut up and never said another word.
Today that would be a different response.
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I’ve always used CIGAR and GUMPS. Works great. And I agree Peter, be very careful who you choose as your mentor or hero in aviation. The pilot that would fly the biggest load out of the shortest strip in the worst weather used to be idolized by young pilots (me included) in Alaska.
mike mcs repair
Registered User
chugiak AK
https://www.avweb.com/aviation-news/some-disinfectants-can-damage-airplanes/
Some Disinfectants Can Damage Airplanes
Some Disinfectants Can Damage Airplanes
Can't see in there;-)
mike mcs repair
Registered User
chugiak AK
BC12D-4-85
SPONSOR
Fairbanks, AK.
https://www.faasafety.gov/files/not...s_Concerns_sheet_-_PA-12_with_PA-18_REV_D.pdf
The reported Piper rudder failures updated w/pics of the damaged parts.
Gary
The reported Piper rudder failures updated w/pics of the damaged parts.
Gary
mike mcs repair
Registered User
chugiak AK
https://www.avweb.com/flight-safety...-time-for-obstructing-accident-investigation/
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Gordon Misch
MEMBER
Toledo, Wa (KTDO)
I wonder what the max rudder deflection was set to. In excess of the type certificate spec?? -18 spec is greater deflection than -12. J3 is greater yet.
BC12D-4-85
SPONSOR
Fairbanks, AK.
Good point Gordon. Non-conformity plus any extra airspeed or prop blast can break things not designed for the loads encountered.
Gary
skywagon8a
MEMBER
SE Mass MA6
IF, This is a contributing factor in these incidents, then it would be improper operation of the controls by the pilot. Under what circumstances do you apply full rudder, other than at low speeds when the air loads are relatively low? It is doubtful that you have the strength to displace the rudder to full travel at a high speed, nor would you likely attempt it as it is not needed.
The certificated rudder stop limit angle is most likely set so that the rudder will not interfere with the elevator at full travel. Just a limit for mechanical reasons.
The only flight testing which is done for determining if the maximum travel is too much is a rudder lock test. AND that is for multi-engine airplanes when there is offset thrust to be considered.
I could believe it was caused by a lot of shaking IF it had an old motor driven Grimes or Whelen rotating beacon mounted. Then the weight on a long shaky arm could have contributed to a failure in this location. Those beacons used to be very common mounted on the rudders. Do any of you know of them being the cause of many rudder failures? I don't. None of the bent rudders in the picture had a heavy beacon mounted.
I'd be more inclined to believe these failures were caused by some external continual forces. Such as the airplane being tied down during an extreme wind storm. Most of you have witnessed what happens to an airplane and it's control surfaces during violent storms. I have and it is scary.
mike mcs repair
Registered User
chugiak AK
didn't see any holes....
the moose like to use planes at lake hood to beat the stuff off their antlers.... one was just recovered .... destroyed the rudder...
the moose like to use planes at lake hood to beat the stuff off their antlers.... one was just recovered .... destroyed the rudder...
Gordon Misch
MEMBER
Toledo, Wa (KTDO)
I can think of a few, hard or impossible to document, possibilities that could aggravate the situation. Rapid rudder reversals in flight, somebody having pushed on the rudder on the ground then pushing it back straight, defective weld at the hinge bracket causing stress concentration, mass-exacerbated vibration, excessive deflection limit (TCDS deflection limit keeps the rudder a long ways from the elevators), metallurgical anomaly (seems unlikely). Undoubtedly there could be other factors, but that's what occurs to me right now.
BC12D-4-85
SPONSOR
Fairbanks, AK.
Stress cracks next to welds....there must be some guidance to reduce that (?). I wonder if failure is gradual or sudden? If gradual any cracking might be hard to see under the fabric. But the metal is exposed at the hinge due to typical fabric application methods so external corrosion focused there is a possibility. The NTSB's metal analysis mentioned will be revealing. If the rudder's shaking some I'd think the pins and bushings would reflect that. Maybe once they get loose it gets worse - the vibration.
Gary
Gary
Crash Jr.
Registered User
Anchorage, AK
Interesting that 2/3 are bent in the same direction-to the left. Would make sense if it was a stress issue to bend that way as you normally use more right rudder than left. Over a long enough period of time maybe?
The balance tab forward rib seems to be the place where it breaks. Possible that the weld was too hot or not enough filler was used and pulled material from the tube. That would account for a loss of material in roughly 40% of the tube circumference at that point.
The balance tab forward rib seems to be the place where it breaks. Possible that the weld was too hot or not enough filler was used and pulled material from the tube. That would account for a loss of material in roughly 40% of the tube circumference at that point.
RVBottomly
PATRON
Asotin County Washington (KLWS)
It's kind of sobering. I'm looking hard at a rudder I welded up a couple of years ago.
BC12D-4-85
SPONSOR
Fairbanks, AK.
How would a fabricator/welder know if the weld compromised the rudder tube?
Gary
Gary
RVBottomly
PATRON
Asotin County Washington (KLWS)
Not really sure except to check for good penetration and maybe warping. I actually tested an earlier version of mine by twisting the top. The ribs buckled first.
SuperCub MD
Registered User
Collins, Wisconsin
So all 3 rudders were on 12's from the same area. Two have the same sort of paint scheme... I ain't sherlock holmes but I would be looking for a connection and the origin of the rudders.
Crash Jr.
Registered User
Anchorage, AK
Normally you can just tell by the color of the weld and checking for undercutting at the sides of the weld bead. Once you get paint or other coating on it's much harder to tell without running a bore scope into the tube to see if there is deformation on the interior of the tube wall.
Crash Jr.
Registered User
Anchorage, AK
After going over those pictures again, I have to take that back. The break point seems to be just up from the upper hinge point, not the rib facing forward. Interesting that it breaks there as there is really no weld to speak of at that point but it is the last point supported by the hinge line going upwards so structural fatigue may be the issue.
Being a skilled fabricator, one has learned just what a good weld is while you are doing it. In a nutshell looking at a weld from the outside, many of the prettiest welds might well have insufficient penetration. There are welders that can not for the life of them properly join .028 wall to .065 tube. Something that comes easy to some but not others.
Inspection by visual means, general shape of the fillet, clean edges, under cutting or a step or sharp edges. Caricaturist tell tails that a skilled welder and inspector can determine if something is good, or needs to be looked into.
If the area is painted or god forbid powder coated it is all but impossible to see the surface texture of the material to judge what temperature the metal had been brought to during the weld process.
mike mcs repair
Registered User
chugiak AK
Tig welds. Usually more likely to crack tube next to weld on thin tube like this. As penetration is very abrupt compared to oxy welds.....
Never seen what shown. But all 3 at lake hood I assume???? Windy place. I like stewarts assumption of gust lock up top most of year.....
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Never seen what shown. But all 3 at lake hood I assume???? Windy place. I like stewarts assumption of gust lock up top most of year.....
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RVBottomly
PATRON
Asotin County Washington (KLWS)
That observation makes sense to me. Reduces the lever arm of whatever is pushing on these. Is there any downside? I can't think of one.
BC12D-4-85
SPONSOR
Fairbanks, AK.
So what next for Cub rudders? Another expensive SAIB or AD based upon a small % of fleet? Something unique was wrong with those rudders.
Gary
Gary
