How Much Systems Knowledge Do We Need?

Without reading through the entire thread I'd just ask if you think there is a point where you just shut off any input because you don't need to know any more about it or are you concerned that the average pilot doesn't know enough to be safe?
 
Silvaire said:
Without reading through the entire thread I'd just ask if you think there is a point where you just shut off any input because you don't need to know any more about it or are you concerned that the average pilot doesn't know enough to be safe?
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Neither. I’m interested in other pilot’s perspectives about the topic and don’t want to add too much of my own.
 
Martin Pauly said:
I'm late to the game... but wanted to share this discussion with Doug Rozendaal and myself, where we explore this exact thread topic from a pilot's perspective:

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I enjoyed the video, thanks for linking it.
Any idea where (if?) I can find a copy of the Air Force publication that Doug mentions "Aircraft Engineering For Pilots"?
 
JeffinNV said:
I enjoyed the video, thanks for linking it.
Any idea where (if?) I can find a copy of the Air Force publication that Doug mentions "Aircraft Engineering For Pilots"?
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Judging by the sample page, I’m pretty certain this is the publication:

Aircraft Engineering for Pilots | AirCorps Library

Preview of the Aircraft Engineering for Pilots document available on the AirCorps Library
app.aircorpslibrary.com app.aircorpslibrary.com
 
I have instructed in everything from a 1948 Eurcoupe to jet liners, and I will offer this. ... every POH/AFM has a systems description section... it's typically simple and short . you must know this well. 2nd, know why a checklist does what it does based on the specific description.

there is stuff you need to know. and stuff that's good to know, a stuff just cool to know.

start with above need to know, and more will make sense.
 
Martin Pauly said:
I'm late to the game... but wanted to share this discussion with Doug Rozendaal and myself, where we explore this exact thread topic from a pilot's perspective:

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Thanks for posting this link, Martin. I had previously come across a video you did with Rozendaal regarding multi-engine training and found him to be quite knowledgeable in a way that is increasingly rare among instructors. He makes some very astute observations here, from a very practical real-world perspective.

There should be more CFIs like this.
 
Roger Wilco said:
A recent conversation about the secret life of controllable-pitch propeller systems has me wondering: How much knowledge about of the inner workings of aircraft systems and components does a pilot actually need? Using propeller systems as an example, do we really need to know about flyweights, speeder springs, servo pistons, etc.? Or could we fly just as safely and efficiently if we believed that the blue knob was somehow connected to a pint-size chamber inhabited by a magic elf who cranked the mechanism into compliance with our demands?
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Returning to this topic, and considering the many replies (thanks, all), the above is the OP. In the conversation I referenced, the other pilot could perfectly describe the basic mechanical operation of a generic constant-speed propeller system as described in PHAK and other training documents. But he didn't have a firm grasp of the why: the aerodynamics involved and the way that the propeller and the engine work together to form a singe propulsion unit. It thus seemed that he was knowledgeable about stuff that doesn't really matter, and unclear on stuff that does.

Personal anecdote: I once flew a large turboprop for a regional carrier. The propeller system was a close relative of the Hamilton Standard 14RF-9 installed on the EMB-120 Brasilia, one of which catastrophically failed in flight resulting the loss of all 23 aboard including a US Senator. With that in mind, I studied every technical document that I could get my hands on to understand the system as well as I could. One fine day, the big Hamilton Standard propeller installed on the (perfectly good) right engine of my airplane decided it wasn't getting enough attention and interrupted my blissful mid-cruise state of satisfaction and wellbeing by--surprise!--unexpectedly feathering itself with a dramatic GRAOWWWOWWOWWWOWWWWOWWWUFFFF...WUFF...WUFF...WUUFF. No manipulation of controls, levers, switches, etc. had any effect whatsoever, and all of the knowledge I had gained by spending hours poring over diagrams and details was totally useless. And I do mean totally useless. Looking back, it would have been enough to know only lever forward = propeller faster, lever rearward = propeller slower, lever behind the gate = propeller stop, to fly the plane with with precision, smoothness, and efficiency.

So, for those who answered "all of it" or something to that effect, how much is "all of it?"
 
Roger Wilco said:
Personal anecdote: I once flew a large turboprop for a regional carrier. The propeller system was a close relative of the Hamilton Standard 14RF-9 installed on the EMB-120 Brasilia, one of which catastrophically failed in flight resulting the loss of all 23 aboard including a US Senator.
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I remember that crash well. We flew the Senator's and his daughter's bodies back home. Our hangar neighbors operated a Dash 8 at that time and if I remember right had to comply with an AD on it because of the crash.
 
Roger Wilco said:
Personal anecdote: I once flew a large turboprop for a regional carrier. The propeller system was a close relative of the Hamilton Standard 14RF-9 installed on the EMB-120 Brasilia, one of which catastrophically failed in flight resulting the loss of all 23 aboard including a US Senator. With that in mind, I studied every technical document that I could get my hands on to understand the system as well as I could. One fine day, the big Hamilton Standard propeller installed on the (perfectly good) right engine of my airplane decided it wasn't getting enough attention and interrupted my blissful mid-cruise state of satisfaction and wellbeing by--surprise!--unexpectedly feathering itself with a dramatic GRAOWWWOWWOWWWOWWWWOWWWUFFFF...WUFF...WUFF...WUUFF. No manipulation of controls, levers, switches, etc. had any effect whatsoever, and all of the knowledge I had gained by spending hours poring over diagrams and details was totally useless. And I do mean totally useless. Looking back, it would have been enough to know only lever forward = propeller faster, lever rearward = propeller slower, lever behind the gate = propeller stop, to fly the plane with with precision, smoothness, and efficiency.
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I will just point out that your knowledge wasn’t bad to have, it simply didn’t benefit you in that particular scenario. There are quite probably scenarios where it could have been of benefit.

The problem is you don’t know which failures to study for in advance.
 
MauleSkinner said:
The problem is you don’t know which failures to study for in advance.
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Raise your hand if you've searched through the NTSB accident database for the airplane(s) you fly, to potentially add to the list of things not to do or to look out for.

For me, flying mostly PA-28s, my primary takeaway was to pay close attention to the operation of the fuel selector. Second was to never jump start one that you're not pretty familiar with.
 
MauleSkinner said:
I will just point out that your knowledge wasn’t bad to have, it simply didn’t benefit you in that particular scenario. There are quite probably scenarios where it could have been of benefit.

The problem is you don’t know which failures to study for in advance.
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We can probably agree that knowledge is good. My perspective is that there is a level(s) of system knowledge that goes beyond what is operationally necessary or useful in any scenario that I can imagine. There is a broad range of experience and expertise on this board, and I am curious about what pilots from different backgrounds think about the matter.
 
Roger Wilco said:
We can probably agree that knowledge is good. My perspective is that there is a level(s) of system knowledge that goes beyond what is operationally necessary or useful in any scenario that I can imagine. There is a broad range of experience and expertise on this board, and I am curious about what pilots from different backgrounds think about the matter.
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Ok…how about

Enough to be able to communicate with a mechanic

Enough to know when to call ******** when the mechanic says there’s nothing wrong

Enough to know when the mechanic is misdiagnosing, for example when he says the engine suddenly blew two quarts of oil all over the cowling because while no oil had been added for months, it wasn’t actually checked post flight yesterday (just ran across those emails the other day. And to be completely transparent, I didn’t call anybody a ****ing idiot until the same thing happened a month or two later.)
 
MauleSkinner said:
Ok…how about

Enough to be able to communicate with a mechanic

Enough to know when to call ******** when the mechanic says there’s nothing wrong

Enough to know when the mechanic is misdiagnosing, for example when he says the engine suddenly blew two quarts of oil all over the cowling because while no oil had been added for months, it wasn’t actually checked post flight yesterday (just ran across those emails the other day. And to be completely transparent, I didn’t call anybody a ****ing idiot until the same thing happened a month or two later.)
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I think that those are all good goals. Can we bring pilots up to that level of knowledge & expertise by the time they get their PPL? Especially with regard to your last benchmark, it seems that accumulating enough knowledge to out-mechanic an A&P (even a bad one) requires a real interest in learning the nuts & bolts, and years of experience.
 
Roger Wilco said:
I think that those are all good goals. Can we bring pilots up to that level of knowledge & expertise by the time they get their PPL? Especially with regard to your last benchmark, it seems that accumulating enough knowledge to out-mechanic an A&P (even a bad one) requires a real interest in learning the nuts & bolts, and years of experience.
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While the last one was a turbine engine, the basic principle applies to piston airplanes at a relatively common level…when do you check the oil? What happens if you put in too much? Does an engine make oil by itself, or would you have to put some in to have too much?

That was really an issue of communication and primacy. The mechanic asked a question with an underlying assumption that wasn’t true, the pilot he was talking to took his word for what had happened, and no amount of follow-up discussion would knock that loose.
 
Roger Wilco said:
Can we bring pilots up to that level of knowledge & expertise by the time they get their PPL?
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'expertise'??? Not to be snarky but most PPL students can't refuel an aircraft. And after waiting at the pump on many PPLs I would say quite a few PPLs still don't have a full understanding of it.

Pilots don't need to know anything about the governor counterweights. They do need to know immediate actions and how to run the checklist.

I would offer that SITUATIONAL AWARENESS is more important that systems knowledge. If you lose the prop due to a hub seal failure the oil pressure will drop and there is nothing you can do about it no matter how much you know. Knowing not to fixate on one issue (remember Aviate is the first commandment) and staying calm enough to address new issues, as well as solve the immediate problem of needing to land are vastly more important skills.

There is a generic 'more knowledge is better' answer, but that's not really the question. The question is are PPLs trained to a level to be able to handle an actual emergency? No, they are not. 99% of PPLs may have had little more than a CFI pull the throttle and say 'engine's out'. Of the 8 CFIs I had the displeasure of 'learning' from none of them ever did a lost comms, electrical issue, simulated fire in the cabin, loss of say rudder or elevator jam.

When I talk to my airline pilot friends they tell me about simulator quals and that after years of sim time they can't remember the last time they actually landed the sim. lol

I'd pay real money to get a few hours in a GA type 3 axis motion sim and spend a day getting all sorts of wierd issues thrown at me... above the 'out of gas' scenario. Not upset training... but say flying/landing via 1/2/3 axis auto pilot, or an elevator jam etc

I will add that one flight out of KRDG in a rental 172 I had a secondary flight control failure. I was practicing stalls and was configured for slow flight, full flaps. After I recovered from the stall the flaps would not come up. Did knowing how the flap return mechanism of the cessna 172 help me? No. not at all. There was no way I was going to adjust microswitches or check wires for power. Check the fuse. popped? no? cycle the flap level again. Flaps move? no. Stay in the white arc, do 80mph (yes, some 172s had mph on the airspeed gauge) to the field and ask for a straight in due to flap failure.

And yes, it was a bad microswitch.
 
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pfarber said:
will add that one flight out of KRDG in a rental 172 I had a secondary flight control failure. I was practicing stalls and was configured for slow flight, full flaps. After I recovered from the stall the flaps would not come up. Did knowing how the flap return mechanism of the cessna 172 help me? No. not at all. There was no way I was going to adjust microswitches or check wires for power. Check the fuse. popped? no? cycle the flap level again. Flaps move? no. Stay in the white arc, do 80mph (yes, some 172s had mph on the airspeed gauge) to the field and ask for a straight in due to flap failure.

And yes, it was a bad microswitch.
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That microswitch might have been one on the flap preselector mechanism, but not likely if the ASI was in MPH. Too old to have the preselector. Most likely it was due to mechanics spritzing the flap jackscrew with oil, or slathering it with grease. The service manuals give all the details about what lube to use and how to apply it, but too many mechanics just ad-lib the maintenance. The oil or grease gets into the flap travel limit microswitches and fouls their contacts so that the system fails.

This is a Cessna flap actuator, after I spent several hours cleaning it up:

1764956556450.jpeg


This is the up-limit microswitch (with the two brass screws in it), the one whose failure means the flaps won't retract:

1764956672334.jpeg
Those switches are not sealed against stuff like this. Mechanics who already know it all and won't read the manuals cause this sort of thing. That grease was into the ball-screw mechanism (which required No. 10 non-paraffinic oil rather than grease, and very little of that) and fouling the balls so they didn't roll but just skidded. They could not recirculate as designed. The grease was in the down-stop switch, too:

1764956893933.jpeg

There are several versions of electric flap actuators and control systems, and they all have different requirements. Mechanics, get those manuals and read them.

And read the regs:

1764957113356.png
 
pfarber said:
Pilots don't need to know anything about the governor counterweights. They do need to know immediate actions and how to run the checklist.

I would offer that SITUATIONAL AWARENESS is more important that systems knowledge. If you lose the prop due to a hub seal failure the oil pressure will drop and there is nothing you can do about it no matter how much you know. Knowing not to fixate on one issue (remember Aviate is the first commandment) and staying calm enough to address new issues, as well as solve the immediate problem of needing to land are vastly more important skills.

There is a generic 'more knowledge is better' answer, but that's not really the question. The question is are PPLs trained to a level to be able to handle an actual emergency? No, they are not. 99% of PPLs may have had little more than a CFI pull the throttle and say 'engine's out'. Of the 8 CFIs I had the displeasure of 'learning' from none of them ever did a lost comms, electrical issue, simulated fire in the cabin, loss of say rudder or elevator jam.
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That’s pretty close to my own perspective, pfarber. I think you nailed it (but I’m usually wrong).
 
MauleSkinner said:
I would submit that it’s at least as important to be able to identify a mechanical issue that should prevent flying the airplane as it is to be able to deal with malfunctions in flight. I think the former could prevent a lot of the latter.
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Totally agree. 75% of a successful flight happens before we slip the surly bonds. Knowing enough about our airplane to identify issues and taking the time to do a thorough preflight are crucial. I just don’t think it’s necessary to know all the stuff that goes on inside the prop governor (one example) in order to determine that it’s secure, not leaking, and connected to the blue knob in the cockpit.
 
MauleSkinner said:
I would also submit that what a private pilot knows when he takes his checkride is very limited. The term license to learn is real. A pilot must continue learning.
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Complete agreement. I still have a lot to learn, which is why I’m here. There is a wealth of knowledge and experience to be found on PoA.
 
Roger Wilco said:
Totally agree. 75% of a successful flight happens before we slip the surly bonds. Knowing enough about our airplane to identify issues and taking the time to do a thorough preflight are crucial. I just don’t think it’s necessary to know all the stuff that goes on inside the prop governor (one example) in order to determine that it’s secure, not leaking, and connected to the blue knob in the cockpit.
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And beyond the preflight, proper systems checks. I’ve known several people over the years who took comfort in the fact that they had a backup vacuum system, but had no clue how to test it or use it. In one case, when I got in the airplane I discovered by actually doing the run up check that the system didn’t work.

Another pilot may have had a dual vacuum pump failure, but we also realized he didn’t understand how his airplane indicated a vacuum failure, so it may have been two individual failures at separate times. He also didn’t understand his systems well enough to know that, had he been in IMC at the time, his autopilot would have worked just fine without the AI or DG operating.
 
MauleSkinner said:
And beyond the preflight, proper systems checks. I’ve known several people over the years who took comfort in the fact that they had a backup vacuum system, but had no clue how to test it or use it. In one case, when I got in the airplane I discovered by actually doing the run up check that the system didn’t work.

Another pilot may have had a dual vacuum pump failure, but we also realized he didn’t understand how his airplane indicated a vacuum failure, so it may have been two individual failures at separate times. He also didn’t understand his systems well enough to know that, had he been in IMC at the time, his autopilot would have worked just fine without the AI or DG operating.
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Yes. This is the kind of operational knowledge that pilots really need.
 
Roger Wilco said:
Yes. This is the kind of operational knowledge that pilots really need.
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Which is roughly the same as my earlier post.
MauleSkinner said:
Enough to be able to communicate with a mechanic

Enough to know when to call ******** when the mechanic says there’s nothing wrong

Enough to know when the mechanic is misdiagnosing, for example when he says the engine suddenly blew two quarts of oil all over the cowling because while no oil had been added for months, it wasn’t actually checked post flight yesterday (just ran across those emails the other day. And to be completely transparent, I didn’t call anybody a ****ing idiot until the same thing happened a month or two later.)
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MauleSkinner said:
Enough to be able to communicate with a mechanic
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As I mull-over the prospect of getting my instructor certificate reinstated, I’m confident that I can get a new pilot to this level of knowledge.

Reaching the level of knowledge necessary to know “when the mechanic is misdiagnosing” does not seem like a realistic goal, at least while training new and low-time pilots.

The illustrations involving vacuum systems indicate a knowledge vacuum (if you will) on the part of the pilot, at the operation level of knowledge.
 
Roger Wilco said:
As I mull-over the prospect of getting my instructor certificate reinstated, I’m confident that I can get a new pilot to this level of knowledge.

Reaching the level of knowledge necessary to know “when the mechanic is misdiagnosing” does not seem like a realistic goal, at least while training new and low-time pilots.

The illustrations involving vacuum systems indicate a knowledge vacuum (if you will) on the part of the pilot, at the operation level of knowledge.
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That operational level of knowledge is what allows one to know that the mechanic is misdiagnosing.
 
Or in the case of airliners, the QRH on a particular pressurization problem could lead you to depressurize the plane with one working pack. But with a better understanding of the system it could have been avoided. Had to rescue the passengers on that one from an airport we didn't normally service.
 
MauleSkinner said:
That operational level of knowledge is what allows one to know that the mechanic is misdiagnosing.
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We may have different concepts of what constitutes operational knowledge. There’s no official definition—I use the term in this thread to describe the level of systems knowledge and understanding necessary to competently operate the machine. Aside from that, I appreciate your perspective and your thoughtful and well-informed posts, here and elsewhere.
 
Roger Wilco said:
We may have different concepts of what constitutes operational knowledge. There’s no official definition—I use the term in this thread to describe the level of systems knowledge and understanding necessary to competently operate the machine. Aside from that, I appreciate your perspective and your thoughtful and well-informed posts, here and elsewhere.
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In my specific example, I consider it to be operational knowledge that a fluid level will not increase without adding fluid. ;)
 
MauleSkinner said:
In my specific example, I consider it to be operational knowledge that a fluid level will not increase without adding fluid. ;)
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Yes, that was my takeaway. Upon initial reading, I momentarily thought you were going to add a clue that the regurgitated oil smelled like Jet A, which would have made for a good systems knowledge example (on some turbine engines, at least). That wasn’t the case, and while I agree that every pilot should understand that an aircraft powerplant is not an oil refinery, that level of understanding lies outside of the scope of my inquiry. ;)
 
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