Aerobatic Assumption

[djpacro]

Page 48 of the May-June 2012 issue of Flight Safety Australia magazine has an interesting article by an anonymous instructor. He took an 3000 hour ex-military pilot out for some aerobatics in a Decathlon and ended up in some scary situations. The point of his article was that he had assumed a certain level of competence. Most of that 3000 hours was in helicopters and it had been 15 years since he had flown a fixed wing aeroplane.

 

Really, the situations were no more unusual than an aerobatic instructor would encounter while teaching aerobatics to some-one. The thing is that an instructor can't relax and simply go along for the ride while pilot in command, no matter who is driving the aeroplane.

 

One comment did surprise me about the roll: " By the time we were inverted, even Ron could see that he had messed it up. However, his fix was something to behold. Having slowed the roll rate to almost zero, Ron did the one thing he shouldn't - and I was sure he wouldn't - he pushed! Unfortunately, he was also a little more forceful than he should have been, and we both lost our headsets as the g-meter registered minus three! I was trying to take control, but because neither of us had our headset any longer, I was yelling, and trying to overpower Ron on the controls."

 

Very strange - Ron did pretty much the first correct action to recover from an inverted nose low situation - I do agree that he overdid it of course. I wonder what the instructor believes the correct action to be?

 

When I was working in the USA I had two similar incidents flying a Pitts S-2B. One was a current Decathlon instructor - he also pushed too hard while doing a roll - minus five g and headsets everywhere. The second was a retired USAF pilot I was taking for a ride at the end of Oshkosh. I asked him how much aerobatics he had done - he said "3000 hours". No, I meant how much aerobatics and he repeated that he had 3000 hours of aerobatics and something like 20,000 hours total. So, I handed over to him and when we got the height he tried a loop or two, falling out of both of them. I said I'd talk him through the next one. I distinctly describing the entry to an inverted flat spin when I took over. He flew us back and I did the landing.

 

He did indeed have the experience he told me but he had never done aerobatics in a propeller driven aeroplane. The moral of the story is never to asssume.

 

"Subsequent inspection showed that the Decathlon had not suffered any damage ... however, it has to be said, we were both very fortunate not to have broken the aeroplane, or killed ourselves." Indeed, Decathlons have been bent, at least, in similar situations. The real scary thing about that story is that it was probably my Decathlon!

 

 

[Yenn]

I don't understand this. The pilot stuffed up and then pushed. What was so wrong. If the pilot got too slow and was inverted in the roll, surely pushing would result in an inverted stall. So how was this the correct action.

 

The article did not state that it as a nose low situation, but if it was I would assume the correct recovery was to roll upright and raise the nose as you went, meaning push at the start of the roll and pull at the finish, plus keeping rudder balanced.

 

 

[dazza 38]

Great read.

 

 

[facthunter]

I had a similar experience with a supposed expert who almost pulled the wings off the plane in an ordinary loop, during a check ride. I won't say much more except there was an element of structural failure resulting, and I am glad the plane was built like a brick $hithouse. It would have taken the wings off a decathlon. Pretty insensitive flying. Falling out of a loop is a bit weird. DJP. Pretty basic. Nev

 

 

[djpacro]

I don't understand this. The pilot stuffed up and then pushed. What was so wrong. ...... So how was this the correct action.The article did not state that it as a nose low situation, but if it was I would assume the correct recovery was to roll upright and raise the nose as you went, meaning push at the start of the roll and pull at the finish, plus keeping rudder balanced.

Yenn, this is my take on it. The article stated:

... and the airspeed definitely too high as we finally pitched up to start the roll. I should have taken over and stopped the manoeuvre before it got any worse ....

Yes.

... He pitched the nose to the horizon—too low by about 10°—and then started to roll. By the time we were inverted, even Ron could see that he had messed it up. However, his fix was something to behold. Having slowed the roll rate to almost zero, Ron did the one thing he shouldn’t—and I was sure he wouldn’t—he pushed!

So, he started with a higher airspeed and a lower nose attitude than he should've. When going inverted you need to push otherwise the nose will continue to drop. He stopped the roll while inverted - consider this - the airspeed was high, the nose was low - the airspeed will continue to increase and the nose will continue to drop - it will get very bad very quickly.The correct action to recover is to push to at least minimise the rate of nose dropping and speed increase. Close the throttle. Roll upright then fix whatever still needs fixing.

There is some good reading on this subject here.

 

Unfortunately, he was also a little more forceful than he should have been, and we both lost our headsets as the g-meter registered minus three!

His training kicked in but he overdid it, not a big deal in an aeroplane appropriate for that sort of training. Instructors require training to get aerobatic teaching approval for a reason as it is common for students to overcontrol etc.

..... If the pilot got too slow and was inverted in the roll, surely pushing would result in an inverted stall..

True if he moved the stick forward to the inverted stall stick position. An inverted stall is no less damaging to one's health than an upright stall (again, the disclaimer of it being in an appropriate aeroplane). My observation is that pilots typically recover naturally from an inverted stall (and any resulting gyrations), if it does indeed happen (another disclaimer - except in some types such as the Pitts).

[Yenn]

I must have misread the article and can't find it now. I knew he was too fast at the start, but missed that he was too fast at the top of the loop and that his nose was too low. Will have to find the article.