Primarily for general aviation discussion, but other aviation topics are also welcome.
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By MichaelP
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#1885080
The objective is to not stall the aeroplane but to unload it while reducing the speed to stop a prop's rotation should the nature of the failure cause vibration to the point the mass of the engine departs the airframe.
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By Ben K
#1885089
MichaelP wrote:The objective is to not stall the aeroplane but to unload it while reducing the speed to stop a prop's rotation should the nature of the failure cause vibration to the point the mass of the engine departs the airframe.


Is this likely to happen on a PA28 or C172?
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By MichaelP
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#1885194
Is this likely to happen on a PA28 or C172?

It’s as likely/unlikely as in any aeroplane with a propeller.

A scenario would be a Cherokee taxying and striking a prop tip crossing from grass onto concrete.
Just a little straightening required, and nobody will know.

A few hours flying later the fine crack in the blade suddenly gives way and a small piece of the propeller comes off.
It only takes a small piece to come off the tip of a propeller to unbalance it to the point where the engine is shaken off its bearers.

I once had a cam follower break up in a Cherokee 140’s O-320. It shook badly, but closing the throttle controlled the vibration.
I had a valve break in a Super Cub with an O-320, it shook too, but not as badly, likewise closing the throttle and shutting down the engine as soon as possible reduced the potential damage. (In this case rolling out on the runway).

Because I had considered what I might do, having read the report on the Owl racer over London, I was mentally prepared for what happened in the Jungmann where I did raise the nose, while switching off the mags, pushing over at around forty knots stopped the prop, kept the engine on the firewall, and reduced further damage. This was a crankshaft failure, something some Lycomings have been worried about.
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By David Wood
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#1885204
There is obviously wisdom in what you suggest, @MichaelP . However, I think @Ben K 's point is that, when set in the balance, the probability of a student ever encountering a situation that required them to deal with a disintegrating prop is very much less than the probability of him or her having to deal with an engine failure in flight. And the probability that an imbalanced propeller will then rip out the engine is also very small - although the results would very probably be catastrophic no matter what the pilot did if the chain of events got that far.

In the case of an engine failure however, especially on the climb-out, the very real risk is that the pilot fails to maintain an appropriate airspeed by immediately adopting an appropriate pitch attitude, and the hazard that arises from that is that aircraft stalls and potentially spins with catastrophic results.

So whilst one cannot argue against doing all that we can to equip a student with the knowledge to deal with any eventuality, given that we all have a finite capacity (expecially when under stress) surely the best course of action is to equip our students with the knowledge and skills to deal with the more probable emergencies, even if that means skating over some of the more esoteric ones.
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#1885217
rusty eagle wrote:Just read the Owl Racer report https://assets.publishing.service.gov.u ... G-AYMS.pdf Presumably a wooden prop is less likely to fall apart?


A very interesting report! And...the second report on the forums in a few days that talks about harnesses and their effectiveness, although in this case the pilot was wearing a harness that didn't quite work as intended.

This might be an incredibly morbid question....a stupid question even...but actually not too tangential to the thread itself, but is there any data showing the % of fatalities that are directly or indirectly caused by impact with the panel?

This really might sound a bit odd, but if you had an engine failure, would your risk of injury/fatality be mitigated by wearing a helmet?

The thing that has always worried me about any sort of forced landing is that my harness wouldn't be as effective as it seems in my pre-flight checks and that if my landing gear were to dig in on contact, I'd be flung forwards and impact the panel; running through it in my head, I've always questioned whether something as simple as carrying a cycle helmet might increase chances slightly (told you it was stupid!)...
By TopCat
FLYER Club Member  FLYER Club Member
#1885232
David Wood wrote:There is obviously wisdom in what you suggest, @MichaelP . However, I think @Ben K 's point is that, when set in the balance, the probability of a student ever encountering a situation that required them to deal with a disintegrating prop is very much less than the probability of him or her having to deal with an engine failure in flight. And the probability that an imbalanced propeller will then rip out the engine is also very small - although the results would very probably be catastrophic no matter what the pilot did if the chain of events got that far.

In the case of an engine failure however, especially on the climb-out, the very real risk is that the pilot fails to maintain an appropriate airspeed by immediately adopting an appropriate pitch attitude, and the hazard that arises from that is that aircraft stalls and potentially spins with catastrophic results.

So whilst one cannot argue against doing all that we can to equip a student with the knowledge to deal with any eventuality, given that we all have a finite capacity (expecially when under stress) surely the best course of action is to equip our students with the knowledge and skills to deal with the more probable emergencies, even if that means skating over some of the more esoteric ones.

In the real world, I can't argue with much of this, given that most pilots probably aren't even interested in preparing for the esoteric ones.

But (and absolutely not implying anything personally at all by this) I hate the acceptance of mediocrity that it implies, nonetheless.

Just out of interest, have you read 'School for Perfection', by Richard Bach? I'd be interested in your comments on it, if so.
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By David Wood
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#1885246
TopCat wrote:
Just out of interest, have you read 'School for Perfection', by Richard Bach? I'd be interested in your comments on it, if so.


I haven't, but I share your rejection of mediocrity as an objective.

The problem with instructing is often, however, one of trying to guage how much a given student can absorb. There are so many times when I want to say something like "OK, Bloggs, let's consider this problem. How would you respond to it? Have you considered doing this?" or whatever. But in practice it's so terribly easy to over-load the capacity of a student to absorb, understand and then re-deploy such knowledge and I've had to learn to sometimes accept that 'the perfect is the enemy of the good enough'.

I fully accept that 'good enough' should not really be the standard that we're aiming at. But sometimes striving for perfection means that we actually achieve neither. That may well say something about shortcomings in my own performance as an instructor, I accept that. But sometimes limiting the bandwidth of what I'm trying to convey is a better way of ensuring that at least the important bits stick.

One of the things I love about instructing is that none of us a perfect at it (ie there is always room for self-improvement); and all students are different. Or is that two things... :lol:
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By TopCat
FLYER Club Member  FLYER Club Member
#1885261
David Wood wrote:
TopCat wrote:
Just out of interest, have you read 'School for Perfection', by Richard Bach? I'd be interested in your comments on it, if so.


I haven't, but I share your rejection of mediocrity as an objective.

The problem with instructing is often, however, one of trying to gauge how much a given student can absorb. There are so many times when I want to say something like "OK, Bloggs, let's consider this problem. How would you respond to it? Have you considered doing this?" or whatever. But in practice it's so terribly easy to over-load the capacity of a student to absorb, understand and then re-deploy such knowledge and I've had to learn to sometimes accept that 'the perfect is the enemy of the good enough'.

I fully accept that 'good enough' should not really be the standard that we're aiming at. But sometimes striving for perfection means that we actually achieve neither. That may well say something about shortcomings in my own performance as an instructor, I accept that. But sometimes limiting the bandwidth of what I'm trying to convey is a better way of ensuring that at least the important bits stick.

One of the things I love about instructing is that none of us a perfect at it (ie there is always room for self-improvement); and all students are different. Or is that two things... :lol:


I totally get all this ^^. And I'm not suggesting that mediocrity is ever an explicit objective, just that the realities of life, keeping businesses afloat, instructor turnover, etc etc, means that there's only so much that can be achieved in a short course.

I expect it can be quite a source of stress for instructors that want to strive for better than good enough, being subject to the realities of life.

After I got my PPL I spent quite a lot of time working on things on my own, pushing the envelope, basically teaching myself to fly to a level of refinement that I hadn't got anywhere near during my actual course - so much so that by the time I got to 100 hours, I couldn't believe how I'd passed anything. But I've always been a bit obsessive like that.

Of course it's been downhill since then... :wink:
#1885262
We don't have to accept mediocrity and should strive for perfection - that's the message in Bach's allegorical story.
But as David says it gets the student nowhere if the instructor insists on perfection before allowing progression (we've heard that before recently). And what is perfect anyway?
I think one of the important jobs for the instructor to do is to somehow instill in the student the understanding that they will never finish learning, that they need to continue to strive to get better and that they will never get to perfection. And that's ok.
That said, I have another take on this. You could say that in any particular situation and with any specified outcome or standard of performance in mind, then good enough is all that's required.
Engine failure in the cruise? Good enough to find a field and land safely without bending anything., Etc etc.
The trouble is that there are a myriad of situations to cope with and our skills deteriorate when not used. The danger is suddenly finding we're not good enough.
The best way to guard against that is to strive always for perfection.
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By TopCat
FLYER Club Member  FLYER Club Member
#1885271
lobstaboy wrote:The best way to guard against that is to strive always for perfection.

The late, great John Farley gave me a wonderful piece of advice once:

"If you ever find yourself with nothing to do enroute, find something. Scan the outside view again... update your choice of forced landing field (you always have one ready, right?).... check the gauges, check the frequencies... think about the next change of heading, or clearance: whatever needs to be done. But you should be fully occupied with the flight, all the time."
#1885272
TopCat wrote:... you should be fully occupied with the flight, all the time."


Yes. Which is why I cannot understand why people listen to music while flying. Or rabbit on to their YT viewers (a commentary later I can cope with) - I keep wanting to yell at them to think about where to go when the engine stops. Or at least to turn their neck a bit to look somewhere that isn't straight in front...
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