jgpo@ihu1e.UUCP (John, KA9MNK) (11/28/84)
< CLEAR! > The other day a buddy of mine at work was telling me of a trim tab failure he had in a Traumahawk. It seems the trim got stuck full aft and he nearly demonstrated a classic departure stall. He got it down OK, though, and consigned the plane to the tender mercies of the friendly neighborhood A&P. While the mechanic was tearing into the guts of the plane, my friend asked a CFI what would have happened if, say, the failure had involved the elevator instead of the trim tab. The answer? "Well, we'd have to write a report..." He told me this and, naturally, this prompted a long session of hangar (office?) flying. We tried to figure out what would happen if one or more control surfaces failed, subject to the constraint that the failure would result in the affected control surface streamlining with the relative wind, i.e., a severing of that surface's control mechanism without it getting stuck. For an aileron failure, both ailerons would streamline. We decided that a rudder failure probably wouldn't be too bad. An elevator failure would be pretty tense, but the plane might be flyable to a controlled crash using trim. An aileron failure would be extremely bad news, but a good pilot *might* be able to survive the crash by trying to keep the wings level with fast and furious rudder work. We didn't even want to think about multiple failures. Does anyone have any ideas on the subject? Or worse, any experience with control surface failure? This could be an interesting subject for discussion, so why not post your replies? John Opalko AT&T Bell Labs Naperville, IL
mlf@druxv.UUCP (Fontenot) (11/28/84)
I've read of a few cases where gliders have been towed off with the elevator disconnected (and since most gliders just have an adjustable spring for trim, there was no trim available either). On several occasions the glider was landed safely by using the flaps for pitch control.
dimeo@lymph.DEC (11/30/84)
The worst failure would be the elevator. I have experienced aileron failure on my R/C models and ( if I figured out what was happening before it augered in) you can control it with prudent use of the rudder and LOOOOOOONG turns. I have seldome been able to recover from elevator failure but then the trim is the same as the elevator control in a model. The rudder failure is the least problem. In models we seldome use the rudder in normal flight and only in the Quarter Scale stuff does it actually become noticeable.
jc@sdcsvax.UUCP (John Cornelius) (12/01/84)
Expires: References: <348@ihu1e.UUCP> Sender: John Cornelius Reply-To: jc@sdcsvax.UUCP (John Cornelius) Followup-To: Distribution: Organization: Western Scientific Keywords: For most Piper aircraft control surface failure is usually fatal. The same is true for V tail Bonanzas. These aircraft are so "crisp" that overcoming broken control surfaces must be done before you actually realize that the control surface is broken. On the other hand, I know of a straight tailed Bonanza who was overflown by a King Aire losing much of his empenage in the process. The aircraft had pitch and yaw stability but no control. The pilot landed using aileron to control yaw (through roll attitude), and power and flaps to control pitch. His knees gave out when he got out of the airplane. Along the same lines, most high wing aircraft can be flown the same way with empenage failure and can also be turned in the event of aileron failure by opening and closing the doors. A friend took me out in his 172 one day and we flew around that way for 1/2 hour. Tomahawks will crash with a perfectly functioning airplane. They are so notorious in fact that the CFI's at our airport claim that the survival rate of primary students who receive training in Tomahawks is about 1/2 that of students trained in C-152s. They become so intimidated by the airplane that they give up the idea that they can learn how to fly. Too bad.
ltn@lems.UUCP (Les Niles) (12/03/84)
[] In article <ihu1e.348> jgpo@ihu1e.UUCP (John, KA9MNK) writes: >... >We decided that a rudder failure probably wouldn't be too bad. An elevator >failure would be pretty tense, but the plane might be flyable to a controlled >crash using trim. An aileron failure would be extremely bad news, but a >good pilot *might* be able to survive the crash by trying to keep the wings >level with fast and furious rudder work. > >We didn't even want to think about multiple failures. > >Does anyone have any ideas on the subject? Or worse, any experience with >control surface failure? This could be an interesting subject for >discussion, so why not post your replies? > > John Opalko Well, not really control surface failures, but i do have some data points and i don't think the failure of any one surface would be that bad, if it just streamlined. A couple of years ago i took some dual from a CFI who has been flying 50 years, and who didn't think much of my (rather horrible) over-manipulation of the controls. To make a point, he offered to take me once around the patch (including take-off & landing) *without touching the control wheel* (the plane was a C-150 Aerobat). I knew better than to argue & said ok. He had the rudder pedals & nose wheel steering for directional control, and the elevator trim to rotate for the takeoff. The turns in the air skidded a lot, of course, but it turned just fine. He flared with the trim also, and added some aileron at the last minute due to a crosswind (wasn't necessary, but he didn't want to unnecessarily injure the landing gear). I'm sure a no-rudder trip would be even easier, except for holding the centerline on takeoff. I also remember reading a story in Flying about a crew that took off in a fairly large twin with *all* the (external) control locks on. They managed to get back by using elevator trim and power to control pitch, and differential thrust to turn. Unless a failure is holding a control surface deflected (as apparently happened with the trim tab), i don't think there'd be much problem. The one that i always wonder about is assymetric flap deployment: One wing with full flaps and the other with none probably would generate an uncontrollable roll. -les niles
doug@terak.UUCP (Doug Pardee) (12/03/84)
[] > An aileron failure would be extremely bad news, but a > good pilot *might* be able to survive the crash by trying to keep the wings > level with fast and furious rudder work. > I can't swear to the following, but the CFI who trained me for my Private license claims that it happened. Would have been in mid-1977 at Phoenix/Deer Valley (DVT) airport. A pilot departed with control locks on the ailerons. Immediately after lifting off the plane began a gentle turn directly toward the control tower. The local controller instructed the pilot to turn away from the tower (I'll bet not too calmly, eh?) and was frantically told that the ailerons were stuck. The controller replied something to the effect of "Use the rudder" and the pilot managed to miss the tower. After clearing the pattern (my CFI was flying an Aerostar, and was the last plane allowed to land), the controller calmed down the pilot and convinced him that a successful return to field was quite possible using rudder instead of aileron. Which it was, with no excitement after touchdown. Doug Pardee -- Terak Corp. -- !{hao,ihnp4,decvax}!noao!terak!doug
scott@opus.UUCP (Scott Wiesner) (12/04/84)
> > The worst failure would be the elevator. I have experienced aileron > failure on my R/C models and ( if I figured out what was happening before > it augered in) you can control it with prudent use of the rudder and > LOOOOOOONG turns. I'm not sure I'd agree with this completely. I have seen models fly that have no elevator, and rely on throttle for control of altitude. I suspect the big problem in the origonal article is that if you have a failure, it's fairly unlikely that your control surface will "weathervane" into the wind and stay stable. As Al Irwin pointed out in his posting about the J-3 crash he witnessed, flutter will probably take over, putting you and your plane on the ground fairly quickly. -- Scott Wiesner {allegra, ucbvax, cornell}!nbires!scott
irwin@uiucdcs.UUCP (12/06/84)
I grew up in northern Michigan, and I can remember the crash of a J3 Cub, due to aileron failure. The cable snapped, and the ailerons fluttered so badly that control with rudder to keep the wings level was impossible. The J3 went into a grove of trees beside a lake where I was in a boat fishing. I quickly rowed to the shore and climbed the bank up to level ground. I could see the plane in the grove, and ran over to it. There was no fire, the plane was on the ground, did not end up in a tree. I helped the pilot and passenger who were badly shook up, to get out of the plane. There was some cuts and bleeding. I ran about a third of a mile to my car, came back as close as I could and got them off to a hospital. In my conversation with the pilot, he said the flutter was so bad that he could not keep it level. They were doing takeoffs and landings in a field across the road from the grove. The plane did a left bank into the grove, which he could not correct with rudder. They had just taken off and were at about 200 feet in a mild climb when the cable gave out. I hope this is food for thought.
brent@phoenix.UUCP (Brent P. Callahan) (12/06/84)
Some years ago I witnessed an amazing escape from elevator &
stabilizer failure on a Cherokee six. The aircraft had climbed
to 8000 feet with a load of skydivers. The first to exit the
aircraft made a bad mistake: he pulled his ripcord as he left the
doorway. His pilot chute deployed his parachute across the top
of the stabilizer as he fell away.
Fortunately, the parachute deployed OK although the left stabilizer
was bent down vertically. The aircraft entered a steep spiral
dive with the rest of the skydivers struggling against building
G's to escape. The pilot was also wearing a parachute. His
escape was blocked by a terrified lady observer who had no
intention of using her emergency chute.
The pilot abandoned his bailout plans. Although the elevator & trim
were completely jammed, he managed to exit the dive and brought
the aircraft in to land with careful use of power and C of G
adjustment by moving the lady up and down the cabin. The
bent stabilizer marked a furrow along the grass runway.
No one was injured and the aircraft was airborne again a
few weeks later.
--
Brent Callaghan
AT&T Information Systems, Lincroft, NJ
{ihnp4|hogpc|pegasus}!phoenix!brent
(201) 576-4439ron@brl-tgr.ARPA (Ron Natalie <ron>) (12/07/84)
> Tomahawks will crash with a perfectly functioning airplane. They are so > notorious in fact that the CFI's at our airport claim that the survival rate of > primary students who receive training in Tomahawks is about 1/2 that of > students trained in C-152s. They become so intimidated by the airplane that > they give up the idea that they can learn how to fly. > > Too bad. I flew a tomahawk for a while because it was cheap. I can say only one thing for them, is that they are slightly easier to land than a 152. They aren't very good at flying, they are good at plummetting. There is a one knot difference between Vs0 and Vs1, however it drops like a rock with the flaps down. It also doesn't have the nice stall taht the Cessna has. It just falls. If it weren't for the rumble strips instralled on the wings, you'd have no warning at all. -Ron
mp@u1100a.UUCP (Mike A Pilla) (12/10/84)
One day, while picking up banners in a Citabria, I managed to hook the sucker
on the left rudder horn giving me full right rudder just as I was pushing over
the top of the pickup. I could not jettison the banner and there was considerable
glider and other flying activity below. By messing around with aileron and
power, I managed to maintain a shallow bank (still attempting to hold full left
rudder with my leg, but no go!) and dove the banner into the ground to break it
With the banner free, I was able to return to land but it took me a while to
get back into the banner groove; for some reason, my next several attempts were
too high.
--
Michael Pilla
Bell Communications Research
201-981-7290
{ihnp4,allegra,pyuxww}!u1100a!mpmp@u1100a.UUCP (Mike A Pilla) (12/10/84)
Some friends used to own a Commanche 250 that wound up with split flaps, i.e.
one full down, the other neutral. They were able to control the roll with
opposite aileron and had sufficient pitch control to take care of the pitching
moment. As I recall, it happend to them twice; the fix after the first
incident apparently did not take!
--
Michael Pilla
Bell Communications Research
201-981-7290
{ihnp4,allegra,pyuxww}!u1100a!mp