Compounded emergencies

[fougapilot]

Compounded emergencies,

Many of you out there who go to Simulator training on a regular basis know that the Feds (both FAA and TC) do not appreciate much when the instructor give unrelated compounded emergencies to simulator trainees.

Well, here is a scenario that happened to me just last Sunday;

We were flying (I was in the LH seat) a Challenger 604 from Montreal to a remote airport (30 minutes away) to pick up passengers and bring them back home. The flight was normal until the time we dropped the gear for landing.

Our first indication of anomalies came as the gear was in transit under the form of a “Gear Disagree” message. Simply put, the gear was not down and locked. However, this situation didn’t last too long, as the message disappeared almost as fast as it arrived leaving us with three green indication looking at each other with question marks on our faces... But this being aviation, the “Hyd 3 Low Pressure” message came out almost immediately to provide answers to our questions. A quick look at the Hydraulic synoptic page (the computer page that indicates all Hydraulic information) showed we had left all our hydraulic fluid (from the #3 system, the most important one) somewhere over the the Quebec landscape.

Ok, no big deal. Seen this a few times in the sim. Our first train of tough is to go-around (the 4500ft runway is short enough with all our brakes, not really interested in trying it with half brakes...) and take a closer look at the airplane. It didn’t take us to long to realize we had little solution but land. The QRH (quick Reference Handbook) says we should land at the nearest suitable airport, se we decide to simply return home with the gear hanging.

We climb to 16 000ft, set up our return route and enjoy the scenery go by at the tender slow speed of 190kias (true, we could have gone as fast as 250kias, but as soon as we went above 210kias the “nose door open” message illuminated). This slower speed gave us plenty of time to review the inoperative systems (Landing gear operation, Nose wheel steering and 50% of our brakes) and to come up with a plan. Since we don’t know for sure where all that hydraulic fluid went, we decide to shut down the APU (this will play a big role later on). Follow the QRH through all the required checklists, complete the manual landing gear extension procedure and set up for a landing on 06R in CYUL.

The landing went on fine, I would even say it was normal. We took our time to slow down the bird to a somewhat slower than usual taxi speed - since we don’t have nose wheel steering, we must taxi the airplane using differential braking which can be a bit harder - and taxi back to our ramp. Again following the checklist, our mechanic goes out and put the gear-locking-pins in before we remove the hydraulic pressure from the #2 system (which is the back up hydraulic system to hold the main gear locked) and we then proceed with the engine shut down.
“Hey! But didn’t you promised a compounded emergency scenario????”

Well the compounded emergency didn’t happened, but listen to this;

Normally, when we shut down the engines on a Challenger, the APU is running full blast. The APU exhaust is located directly underneath the RH engine whist the Luggage door is located underneath the LH engine. 70% of the time, we hear the LH engine noise when we do our shut down simply because we (either the crew or the ground crew) go for the luggage before the engine spools down completely. However, we never go under the RH engine because of the hot APU exhaust. But this time, our APU is not running and our mechanic is curious as to what happened to our #3 hydraulic system. So as soon as we shut down the engines, he proceeds around the airplane to the #3 hyd access panel underneath the RH engine providing him a clear “listen” to the engine spool down.

What he heard was WAY OUT OF THE ORDINARY!!! The engine is making a severe grinding noise as it spools down. Further investigation showed that the engine gear box was in the final stage of destroying its self... And if the gear box goes, so does the fuel pump/FCU (fuel control unit) and the engine simply stop.

It is somewhat difficult to evaluate how long the engine would have lasted. 30minutes? 5 hours? Who knows? But it was severe enough for the airplane to be grounded immediately awaiting an engine change.

So imagine our landing should the engine have failed...

Single engine,
Flaps 20deg (20%increase on landing distance), approach speed increased by 14kias
On Thrust reverser I can’t use because I have no means of keeping the airplane on the centerline..
No nose wheel steering
0% brakes or a few brake applications (accumulators) but without antiskid, (250% increase on landing distance)
Limited flight controls; One aileron, one elevator (as in one side of the elevator)

Come to think of it, I’m glad the engine decided to last long enough for us to land... The QRH provides guidance for a dual Hyd failure (system #2 & #3) but not for a single engine approach with system #2 & #3 failed. I'll have to try it next time I'm in the sim...

So, next time you go to the Sim, give your instructor a break if he gives you compounded emergencies that “look” unrelated...

Cheers,

F

[pilotbzh]

Good Job fougapilot, Did you buy a few lottery tikets after that one?

[fougapilot]

Pilotbzh,

Thanks, but since this is a "could have" scenario (the engine did not actually quit... thank you very much), I can't say I deserve any glory. And no, I do not buy lottery tickets. I much prefer keeping my luck for more important venues

F

[shankdown]

During a flight I had a couple of years ago on a Lear 36, one of the engine driven hydraulic pumps packed it in. We're not sure what phase of the flight that happened in, but there was no mistaking that it stopped somewhere along the line. There was no indication of this having occured, because there is only one hydraulic pressure guage, and the pump on the other engine was sufficient to keep it topped up. Subsequently, we had low oil pressure indications on the other engine, and proceeded to shut it down. So now, there were no hydraulic pumps operating at all. We didn't notice the lack of hydraulic supply until we were turning final, because the hydraulic pressure we did have was sufficient to get our flaps to landing position, and our landing gear down & locked. The gear doors, however, couldn't close, so some nice little red lights help point us to it. A quick flip of the aux hyd pump switch, and they closed. But had there been enough pressure left over to get the gear doors closed, its possible that we may have missed the tiny guage reading zero hydraulic pressure, and been in for a rude awakening when we landed and had the brakes hit the floor as we roll down the runway with no deceleration. Multiple failures do occur, and they can compound to result in a bad day. Its just a nice thing when all the "what if's" remain just that: "What if's?" and not "If only's..."

[xsbank]

Hey Fouga, interesting story! That's the first gear-box failure I've heard of. And actually the first total failure of system 3 too! Let us know what failed?

[A Regulator]

Good story, I enjoyed reading it and from what I remember from the ACP manual multiple unrelated emergencies are not to be given on check rides. I always enjoyed the multiple system failures (to a point) as it tested your knowledge of the systems etc. This is good especially if you have been on the aircraft for several years and know the aircraft, sim instructor etc and you have completed the program.

[Riverman]

fouga pilot

How did a gearbox failure result in a complete system failure? I don't know a thing about the 604 or it's engines, but one would think that a gearbox failure would mimic an engine failure in terms of loss of acessory drive, and not be catastrophic due to redundancy offered by the other engine. Or did it "shed" some gears and rupture a line?

[fougapilot]

First of all, the gear box didn't fail. It was on its last miles before failing. Gear box can fail in different ways; if the drive shaft simply breaks, then you lose all associated systems including the FCU/fuel pump which would result in an engine spool down. However, if the gearbox "destroy" itself (my mechanics words, not mine. He was actually surprised we had ZERO cockpit indications of an engine problem) who knows how the associated systems would be affected. One of the smaller unit connected to the gearbox (on a CL anyways) is the hydraulic pump. If all hell breaks loose who knows what would really happen with the hydraulic fluid. If all the fluid goes out the tail pipe, so goes the hydraulic system...

Back when I was an Instructor at FlightSafety, I remember speaking to a crew than had a gearbox destroy itself just as they were coasting out over the Atlantic. They had to secure the engine (it gave them an indication of engine fire...) and return to Gander. When the mechanic inspected the engine, there was a hole in the gear box. They lost all engine oil, but can't remember if they also lost the hyd fluid.

So, what caused the #3 failure? A simple "O"ring...

On the CL604 (and 600, 601 for that matter) the #3 system operates a lot of subsystems; gear actuation, inboard brakes, nose wheel steering, both ailerons, both elevators and rudder just to name a few. When the landing gear is activated, there is insufficient pressure to go around. Priority must be given to the gear as it demands a lot of fluid/pressure to work. Now, this doesn't mean that whilst the gear is moving we loose the flight controls; all flight controls are powered by at least 2 independent hyd system. We simply temporarily remove some of the #3 hyd pressure to all flight controls. In any case, on the "priority valve" (don't ask me how it works - PFM Pure F$%^ Magic) there is a bunch of "O" rings and one of them decided to quit his job. When we lowered the gear, the increase pressure caused a leak and all the fluid went out. When we landed, the quantity gauge read 2%.

Cheers,

F

[just curious]

I think my victims this weekend thought of them as "Confounded emergencies"

[xsbank]

Priority valve on system 3 - because of the importance of the number 3 system, if the pressure begins to fail or it drops below 2100 psi (normal is 3000) the priority valve directs all the remaining fluid and pressure to the flight controls (sheds the gear).

Any photos?

[Rockie]

"Many of you out there who go to Simulator training on a regular basis know that the Feds (both FAA and TC) do not appreciate much when the instructor give unrelated compounded emergencies to simulator trainees."


More or less, but there are cases where it is permitted for checking. In training anything goes provided the minimum training as required by the CAR's is provided. Here is the actual wording from the script development section of the ACP manual:



6.3.19 Abnormal/Emergency

The introduction of the system faults requires the greatest planning in the creation
of a script. The major criterion is that the faults be realistic and not lead to multiple
unrelated failures. The type and number of faults is also an area of significant
discussion. An ACP and/or Air Operator may wish to cover every exercise in the
QRH over a period of time while others will be restricted somewhat by the
complexity of the aircraft, the fidelity of the simulator, and time limitations.
The general consensus is one major and one minor abnormal per PF.

Given the vast differences in aircraft types specific guidelines are not possible.
However, the following should provide some direction:

(a) Minor Abnormal: The aircraft system fault requires crew recognition and
simple action(s) to remedy. The fault is related to a single system or has
minimal impact on crew or aircraft operations;

(b) Major Abnormal: The aircraft system fault requires crew recognition and
action. The fault may affect several systems and affects crew and aircraft
operations;

Note 1: Faults that do not require crew action, advisory or crew awareness
messages, will not be considered to meet this standard unless
subsequent aircraft operation is affected.

Note 2: A Medical emergency will not be considered an aircraft abnormal
but may be recorded as a fault under the Flight Test Report,
section 6 for tracking purposes.

(c) where a choice of faults exists the most demanding and assessable fault
should be chosen;

(d) faults should be introduced at a time where they can be followed to their
logical conclusion;

(e) no unwarranted actions or events will be introduced for training or exposure
purposes. Training credits cannot be obtained during the PPC;

(f) dual failures are acceptable where a single QRH or ECAM/EICAS
procedure exists to correct the fault;

(g) multiple failures are acceptable where they are the result of a single failure such
as an engine failure. A second unrelated fault might be introduced where the
first fault has been actioned and is benign for the remainder of the leg;

(h) system faults should change with each recurrent script period and may be
compatible with the recurrent training matrix, if applicable. The exact fault
from training day is not recommended. In addition, faults from systems not
on the training matrix for that period should also be introduced;

(i) system faults should be different for each recurrent script;

(j) system faults should be different for each crew member;

(k) fault pick lists may be used provided each list is identified and once
selected the ACP continues with the fault on that list. ie. Option A or B lists
may be incorporated but once the ACP starts on the A list he must continue
with the A list; and

(l) engine fires and or fire/failures are required by regulation and do not count
as system abnormalities.

[A Regulator]

Glad to see you using the 9th edition of the ACP manual and for those who do not use scripted rides the wording for "briefing in Simulators" is that multiple, unrelated failures will not be required, but the candidate must be prepared to take corrective action on related failures (ex. loss of hydraulics or electrical supply due to a failed engine);

However those words are not used if doing a check in the aircraft as the words are the manner in which simulated emergencies will be introduced by the ACP;
All such events are to be preceded by the word “simulated”;
(j) that the candidate will be required to demonstrate any normal or emergency procedure applicable to the aircraft. The candidate's technical performance will be assessed in accordance with the:
(i) aircraft flight manual, aircraft operating manual or pilot operating handbook;
(ii) CAR Part VI and VII;
(iii) Operator's operations manual; and
(iv) Operator's SOPs;
(k) the actions to be completed in the event of a real emergency or malfunction; and
During the ride, the candidate will be expected to respond to any event and carry out any required emergency procedure in the manner specified in the appropriate company guidance document (AOM, SOPs, etc.); should a real emergency occur and the Pilot in Command assume control of the aircraft, the candidate will acknowledge and respond to directives from the Pilot in Command

So it is important that crews receive a proper briefing so they know what to expect.

[xsbank]

I've always taken the position that a candidate is doing a ride to demonstrate that he has the required knowledge to operate the a/c safely, not that I am able to load him up with numerous unrelated failures until he fails. What does that demonstrate? Besides, there is only so much time available for training and its not possible to come up with every compound failure. Single and Multi-engine MAPPS, low-energy MAPPS, V1 cuts, emergency descents etc. etc. keep the gang plenty busy.

Its also why, as long as I'm fast enough, when I'm running the sim I don't actually allow anyone to crash if they pooch something in training. What does that prove? Besides, it upsets me.

[just curious]

I'm with X, I won't overload a candidate on a ride; but getting an experienced candidate in for a training session, it is amazing to see how much you can load up in the way of failures,and still have them flying.

[Airtids]

Great thread!

Another one of my pilots and I were down in Wichita last month for Flightsafety, and I remember after about day three looking at each other and saying "Man, isn't it going to be nice to get back home and fly our machine with nothing wrong?! Hell, even one failure is going to seem pretty easy!".
Sim training makes me appreciate two things: How compounded emergencies can get outta hand really quickly; and the value of excellent maintenance.