Failing a System for training/test

[Duchess_Driver]

Having a discussion with one of my senior instructors revolving around the practice of 'rendering a system inop' for training and testing purposes.

E.G. Pulling the gear motor CB to simulate failure of the undercarriage.

Allowed/Not allowed? If so, where is the appropriate regs to say 'No'

Can't find much in the UK CAA FEH or any other publications about this.

Comments, thoughts...

[nick14]

Depends very much on the type/variant. Pulling the gear CB in the duchess doesn't do much harm I believe (last instructor did it to me) however certain types (like the pa24) performing a manual gear extension upsets the engineers as they have to jack it up to reset the gear.

A bit of system knowledge, TEM and ensurin you have the students learning objectives in mind. How much will they benefit, will they truely understand the intended points or will they take a dangerous lesson home, it's ok to mess around with the aircraft systems my instructor showed me.

Personally I try and avoid it unless there is a decent simulator which often gives a better scenario and lesson in non-normals.

[Big Pistons Forever]

I know a guy who pulled the circuit breaker for the gear on a light twin. The circuit got disrupted, things got busy and a gear up landing ensued. The gear horn, the last line of defence was of course disabled when the circuit breaker was pulled.

My 02 cents

If it has a switch you can consider turning it off, but never pull a circuit breaker.

My pet peeve is that a lot of these emergencies are not handled realistically. That is the cb is pulled the stude rattles off the checklist and then the system is restored and on to the next emergency.

In the real world the initial emergency checklist items are often the easy part. Things get hard when you get to the "so what do I do now" pilot decision making.

I am a strong believer in having one simulated good emergency per flight but what's broke stays broke until you have landed, including having a discussion on how to write the snag.

[BEagle]

If it has a switch you can consider turning it off, but never pull a circuit breaker.

Quite so. A circuit breaker is NOT a switch, it is a circuit protection device.

Ever since the Halifax SwissAir crash, commercial operators have been far more reluctant to reset a popped CB than hitherto. We used to permit one reset only; if it popped again, it was to be left.

Unlike my navigator in an F-4, who reset the same CB some 8 times until he queried it with me.......:uhoh:

[Genghis the Engineer]

I think that the points about system knowledge and TEM are most relevant here.

Two that I've seen (or used) most are disabling a VOR being used for navigation, and pulling the fuse/CB on electric flaps. Both are survivable - if the CB won't reset the aeroplane should still be landable, and there are other ways to navigate. But equally both help a student develop the ability to spot faults and deal with them without jeapordising the overall flying task.

You can see the issue with pulling the gear CB - if that doesn't reset, then in some aeroplanes that could turn into an expensive hobby as it did for BPF's chap.


Seem to be that there's no explicit regulation about this, so the real question is whether the action of disabling something can be construed as endangering the aircraft, or not. I don't see a difference between telling the student to do a flapless landing, and pulling the CB so that they have to spot the need from themselves - from a safety viewpoint. But from a learning viewpoint there are advantages.

G

[Whopity]

The RAF lost two C130s, XV180 at Fairford in 1969 and XV198 at Collerne in 1973 before they deceided it was not a good idea to fail systems for real.

http://lowres-picturecabinet.com.s3-eu-west-1.amazonaws.com/51/main/30/1090709.jpg

[Big Pistons Forever]

I think that the points about system knowledge and TEM are most relevant here.

I don't see a difference between telling the student to do a flapless landing, and pulling the CB so that they have to spot the need from themselves - from a safety viewpoint. But from a learning viewpoint there are advantages.

G

Your point about system knowledge is a very important one. Sadly the level of understanding of even the basic systems in a GA aircraft is pretty low for most of today's light aircraft instructors

Re the flaps, I respectfully disagree with pulling the cb. It is not a switch and should not be used as one. In any case most light aircraft do not have pull-able cb's. They will likey have the flush style which only protrude after they have tripped.

For simulating flap emergencies I do 3 simulations of flap emergencies that have actually happened to me.

1) A jammed flap lever. When the student goes to put the flaps down I tell them the lever won't move

2) The flaps went down and then retracted themselves uncommanded ( I select flaps up as soon as the flaps reach the selected extension.)

3) The flaps went down and then would not come up.

No 3 is an excellent drill. Set the student up for full flap landing and then go around at an altitude of about 300 feet AGL. When the student goes to select flaps up tell them they have selected flaps up and nothing happened. They now have to get the aircraft to climb and fly the circuit to landing with the flaps full down. (Note in a C -150 with 40 degs of flap out the airplane may not climb at all so be prepared to take over and retract the flaps before an unsafe flight profile is established.)

[Cobalt]

I agree on the systems knowledge - if you fail a system by pulling the circuit breaker you need to know what you are doing. But if you are teaching, say, emergency gear extension, you hopefully know the gear system quite well - otherwise, what do you teach the student???


I disagree on that it should not be done (sorry for the double negative).
I will happily pull CBs in training provided - and that is important - I can safely complete the flight if it cannot be reset for any reason, which might well be that it is 30 years old and has not been moved in the last 15 of these. So I would NOT pull the flap CB with full flaps down, but would do it with flaps up.


There are a couple of training scenarios where it is, IMO, essential to pull the CB.


(a) Training a procedure that cannot be performed with the system powered. Example


On an aircraft that has an emergency gear extension procedure that can be done without requiring follow-up engineering work (such as disengaging cranks, refilling blow-down bottles etc.) I would argue that it is part of any good conversion training (or initial retractable training) to actually perform an emergency extension. The way it feels, the amount of pumps on the manual pump / cranks on the handle etc. are all valuable training, and there are some interesting teaching points for beginners. You could switch off the master instead, but that, IMO, is not great given you lose the radios during that time.




(b) Training the recognition of an abnormal condition


If possible, at least once per student, I secretly pull the gear CB on downwind (e. g., in a PA28 Arrow). One of my initial retractable students said "three greens" without looking. Nothing drives the message home as calling for the go-around at 100ft...


As for the "flaps stay down" scenario - I simulate this by secretly reselecting flaps down. But more than half of the students notice.

[Big Pistons Forever]

If possible, at least once per student, I secretly pull the gear CB on downwind (e. g., in a PA28 Arrow). One of my initial retractable students said "three greens" without looking. Nothing drives the message home as calling for the go-around at 100ft...

.

Well landing gear up by cacking up the go around from 100 ft would drive home the message pretty well too, but I am guessing not in the way you intended....

Personally I think it is pretty silly to pull the gear cb on a Pa 28 Arrow when you can get the exact same effect, no green lights, just by turning on the nav lights, a bit of systems knowledge I would hope you would know.....

[Cobalt]

The instrument light solenoid / nav light combo thingy is to the left of the master switch and I have not yet figured out how to operate it without the student noticing. I make them fully aware of the issue by switching it on before they go out to do the pre-flight check [it is also part of the systems briefing, but by the 3rd sortie or so they forget...].


Also, the CB pull prevents the actual gear extension, so this simulates a different failure; the reason for carrying it on beyond base is to see


(a) do they pick up the clues (lack of gear noise, lower power)
(b) do they do a reds-blues-greens check at short final


100ft is probably a bit too low; I have no real target height but I want to give the student every opportunity to figure out something is wrong. So far only one carried it that far...

[dubbleyew eight]

interesting thread.
during my later training the instructors were always dicking around behind the fuses disconnecting something.
you'd get the question toward the end of the flight, "how are we going for fuel?"
you'd look down to both gauges reading zero.
they'd be waiting for the panic to set in.

I took off with 2 1/2 hours of fuel, we're 50 minutes into the flight, we've got no stream of vapour out back (cap left off) hmmm bit over an hour remaining.

I had so many things failed during training that I never rely on anything but my mental picture and the engine note. the moment that engine note changes I swing into action.

I have always loved flying but I thought aeroplanes were the dodgiest pieces of engineering going during my training. especially since I've owned an aeroplane I have been amazed at how reliable aircraft actually are.

failing systems during training does breed an attitude of, hmmm trivial fault, I'll keep it flying anyway.
if you want legally terrified subservient pilots dont fail systems.:E

[Big Pistons Forever]

The instrument light solenoid / nav light combo thingy .

Sure nice to see in-depth system knowledge used to correctly explain a system :rolleyes:

You can start with learning what a solenoid is and what it does :ugh:

[Cobalt]

Sorry. Meant rheostat, I plead time of day... :( You know what I meant, though...

[Big Pistons Forever]

Sorry. Meant rheostat, I plead time of day... :( You know what I meant, though...

You are still not right .......

[Cobalt]

What but a rheostat/switch combo is it? The left rheostat part controls the radio or instrument lights (don't remember which, the one on the right does the other lights). In addition, the left one does the nav lights and also dims the gear indicators.

The point is, given that in the PA28 it sits behind the throttle it is quite hard to operate without the student noticing.

And how about this - part of ME training is shutting down and re-starting an engine in flight... That sure as anything is a systems failure, with appropriate caution (3000ft AGL, close to airport etc). The examiner just closed the fuel cock on me without me noticing nor expecting it. That single "event" was more valuable than all other simulated engine failures together because it included the "WTF is going on" moment.

[Big Pistons Forever]

The gear lights get full bus voltage and thus are full bright except when the nav light switch is selected on. Switching on the nav lights send bus voltage to the gear lights through a resister which reduces the voltage and thus dims the gear lights. All other annunciator warning lights are dimmed by the instrument light rheostat

Not a huge point I admit, but if you are teaching on a complex airplane you should know how things work especially if you are messing with a system. The resister is shown on the simplified landing gear electrical schematic. I would suggest you review it with somebody who knows how to read an electrical diagram.

A couple of other things somebody teaching on the Arrow should know

1) Why should you avoid retracting the gear while the aircraft is in a turn ?

2) You are flying along and the airplane landing gear suddenly indicates down with out you doing anything. What are the possible causes ?

3) You have to use the automatic gear extension but when you follow the POH emergency gear you get a green light only on the mains, but not on the nose. What should you do ?

4) Why is it a good idea to check the ammeter after you have retracted the gear.

5) Approximately how long should the landing gear take to retract or extend. Why should the pilot care about this ?

[dubbleyew eight]

should that post be on the 'firm grip on the non essential' thread :E

[Big Pistons Forever]

should that post be on the 'firm grip on the non essential' thread :E

Call me old fashion but I think it is reasonable that an instructor should know what the function of a Solenoid, a Rheostat, a Resister; is and where they would commonly be found in aircraft systems, especially if you are doing advanced training in complex aircraft......

[Duchess_Driver]

Some interesting responses, but still no guidance as far as regulatory authority is concerned....

Wholeheartedly agree that TEM plays a big part in management of emergency scenarios and from an instructors point of view a secure failure response plan should be in place way before the hand goes anywhere near a CB to disarm a system.

Can't help thinking that ADM development is reduced by "tell me what you'd do if...." type questions. As had been said, a big part of management of the developing situation is the recognition of the failure in the first place, followed by a sound decision and response plan being auctioned in the heat of the moment by the candidate.

Again, systems knowledge and understanding the different failure paths is something that any PILOT should have a firm grasp on - regardless of what it is that they're flying, let alone teaching in!

Thanks