Check Flights and Pulling Circuit Breakers

[320busboy]

Definitely a bad idea.

Post 320 Airbus moved the most circuit breakers to the avionics compartment. The ones left in the cockpit are resets, not power trip cb’s. Except some for window heat and whatnot. 350 went one step further and split the critical systems channel A/B between electronic circuit breakers and physical circuit breakers. Either way you can’t get to them in flight.
cabin cb are not much of a drama to reset in an attempt to recover some lost convenience items unless they were found tripped. Then they are to be left alone.

[Checkboard]

Apparently it was quite common practice on the 3 holer back then, Checkboard.
They'd pull the CB to prevent slat deployment, then move the flap lever to extend the flaps to about 2° and enjoy the ride. The investigation didn't prove anything untoward but I think they were concerned there were a few porky pies being told when they realised the CVR had allegedly been erased after landing.

it was an old wives tale in the company, and the Captain admitted that he had heard of it (as had everyone else), but never attempted it.

Boeing testified that the slats couldn’t deploy any other way (as they would, protecting their aircraft’s reputation. )

The CVR was found erased, and this was in the days when there was an erase button in the cockpit, specifically put there for pilots to erase the tape after a safe flight, as a sop to concerns that management would spy on flight decks in the early days of CVRs. The Captain admitted that it was his habit to erase the tape after normal flights, as did many others back then, but that he didn’t/ couldn’t remember doing so on this flight.

Those items lead to the Captain being accused, BUT

The “pull to CB to deploy the flaps a bit for better high alt cruise” was a stupid idea to anyone that gave it a moments thought. It meant that Boeing would have completely stuffed up the wing design for it to work.. and of course, when the idea was tested, performance was significantly worse, so anyone stupid enough to try it would know it didn’t work.

The slats were shown to deploy independently on failure of the jack, and that happened on other aircraft, despite Boeing’s assurances. The jack was never found on the accident aircraft.

The “erase” switch on the CVR only worked with weight on wheels and park brake set, and the gear was damaged so much that there was no weight on wheels signal, so the Captain couldn’t have erased the CVR even if he wanted to. The erase function was shown to operate with an electrical short, however, and the aircraft damage was such that many items were shorted.

The poor guy saved the aircraft with an amazing bit of flying after a serious upset, and was vilified for it, based on BS accusations

[ivor toolbox]

Originally Posted by Lazyload

How else can you practice a manual gear extension? Pull gear motor cb, select gear down, nothing happens, pump gear down manually. Not that you need to do this every check flight but it’s nice to know that it works.

That requirement is taken care of by your maintenance schedule. Outside of that Don't play with things!

[ivor toolbox]

Originally Posted by Lazyload

How else can you practice a manual gear extension? Pull gear motor cb, select gear down, nothing happens, pump gear down manually. Not that you need to do this every check flight but it’s nice to know that it works.

That requirement is taken care of by your maintenance schedule. Outside of that Don't play with things!

[Pugilistic Animus]

Hoot Gibson was the PIC on the alleged 727 CB pull.
Unless it's a QRH procedure I would never pull a CB based upon all of the reasons written above. NWA also learned, in a severe lesson, about CB pulling where the pilot pulled the CB for the TO configuration warning and then tried to takeoff without the flaps/slats set for TO. Everyone perished save one baby.

[fdr]

Originally Posted by john_tullamarine

Early BOAC days of the "real" Boeing 707

RAAF Crash 1991 Australia Boeing 707 - YouTube .. getting on to 30 years ago. A sobering result of doing things which are not appropriate to do in an aeroplane.

Years before the accident I had the IP of the 707 accident with me as a copilot, and he was a very competent driver on our type. Every day flying, we were asymmetric, and sometimes with 2 shut down. What was missing with the 707 was the general awareness of the effect of the flight control system, and swept-wing, when they did a VMC Air demo with the rudder boost off. The aircraft stalled well above the expected stall speed, With no rudder, the yaw led to roll moment that was offset with aileron, which introduced the spoilers... and so the wing was loaded up considerably. when the plane stalled, it rapidly rolled off, as in autorotation rates, fast enough to throw an outboard engine off the pylon. Some good people were lost from learning to bleed, and the IP was led down the path by his familiarity with straight wing asymmetry, and the differences of a swept wing with supplemental spoiler roll control.

I do type ratings and training in various jets and, like flying helicopters, it is safe until it suddenly isn't, care has to be taken to ensure that risk is not excessive. In an ideal world, sims would do all the heavy lifting.

[fdr]

Originally Posted by Checkboard

BUT

The “pull to CB to deploy the flaps a bit for better high alt cruise” was a stupid idea to anyone that gave it a moments thought. It meant that Boeing would have completely stuffed up the wing design for it to work.. and of course, when the idea was tested, performance was significantly worse, so anyone stupid enough to try it would know it didn’t work.

The slats were shown to deploy independently on failure of the jack, and that happened on other aircraft, despite Boeing’s assurances. The jack was never found on the accident aircraft.

Not sure I agree with one part of your statement. There is an STC that was done on another quite similar wing that resulted in a slight deflection of the TE flap in the flaps up configuration. Two effects resulted; the fowler flap translation resulted in an increase of wing area, in the inboard section of the wing and it increased camber. The camber increases CL,/AOA. area increases total lift. the outcome was an improvement in performance at altitude. That STC is still available for sale for the large transport. On a mid-size jet I still occasionally drive, it has a similar STC, where the camber is altered, along with area.

Pulling a breaker to get that effect is not a brilliant idea, but the effect, when obtained by a design, is reasonable.

Back in the day, we used to practice some stuff in the aircraft, some stuff like 2 engines out on one side for approaches and GA etc.. the sim we had at the time was a FBT and was not deemed acceptable for completing all training. One bright happy day we were tooling about burning tax dollars and the new engineer was in the seat, and the check engineer wanted to show the effect of an uncommanded light off on restart. We had engines shut down on almost every flight we did, and the one thing this plane was not short of was thrust, we could get to VNE with 2 engines shut down, at near sea level. So the Fuel/Ignition CB for the shutdown engine was pulled by the check engineer. when the engine was started up, the new engineer noted that as soon as the feather button was pulled out, the prop spun up, RPM went past 16% and the engine lit off, the new guy handled this happily and the engine accelerated up to normal RPM and stabilized. The newbie checked the breakers and confirmed that the #`1 F&I breaker was out. As we were discussing the implications of that, (the Fuel switch was still turned off.... ) the 3rd engineer walked up from the back, and reset the breaker.
"Engine Failure, #1!"
"Roger, Confirm the Engine... "
"Failure #1 Engine Confirmed...."
"Noted, E Handle #1 Please....."
"Confirm !", E Handle 1 Confirmed....",
"E Handle Pulled".

Coffee break time.

The rest of the flight was quiet, the 3rd engineer sat back in despondency, the check engineer was not much happier.
The newbie did good, and never let anyone pull breakers on his plane.

Stuff happens.

[PaulH1]

If a switch or breaker is going to fail, it will almost certainly happen when it is operated. Breakers have a finite life so never operate one in the air unless it forms part of a checklist. By all means pull them when on the ground, but abnormal/emergency training in the air is nowadays best done in simulators only.

[turbidus]

this like simulating EO by turning off an engine!

[Driver airframe]

https://aviation-safety.net/database...?id=19770317-2

like this ?

[fdr]

Originally Posted by Driver airframe

https://aviation-safety.net/database...?id=19770317-2

like this ?

that's an interesting event. The failure of the downwind engine in a strong crosswind has a more dynamic yaw control requirement than an upwind failure. While the MLG is on the ground, the downwind engine failure requires a reduction in downwind rudder input up to an into wind rudder input to counter the thrust asymmetry, but as the MLG comes off the ground there is a need to introduce more upwind rudder to stop the yaw from asymmetry. Any timing delay will result in yaw and roll excursions and a squirrely ride. At 20' and 20 degrees roll, the wingtip was really really really close to the ground too, not just #1.

[Eclan]

Originally Posted by Checkboard

it was an old wives tale in the company, and the Captain admitted that he had heard of it (as had everyone else), but never attempted it.

Boeing testified that the slats couldn’t deploy any other way (as they would, protecting their aircraft’s reputation.)

The CVR was found erased, and this was in the days when there was an erase button in the cockpit, ...........................................and the aircraft damage was such that many items were shorted.
The poor guy saved the aircraft with an amazing bit of flying after a serious upset, and was vilified for it, based on BS accusations

Well, that's certainly one evolution of the story over all the years. It doesn't sound unreasonable.

[cappt]

There's no authorization anywhere to pull a CB unless it's in the QRH in reference to a mechanical abnormality.

[Tinribs]

I was passing through Prestwick, sort of 70,s, when there was a BAC 111 "parked" nearby in a sorry state. The story was that training for flapless landing they had pulled the cb to stop the flapless din. Unfortunately that cb also gave the gear up warning. The rest is history except the co pilot was reported to have said after impact "don't they have tall firemen here

[eagle 86]

Not high performance fw but years ago I tricked myself. Instructing on the SK50 helo pre simulator QHI's pulled cb's for systems failure.
I was checking a pilot out during an anti sub exercise. There is an AC cb panel just below the collective on the left side.
If pulled one cb took power away from the flight control system immediately with subsequent flight control problems.
Another cb took power away from the gyros controlling the flight control system with flight control problems some time later after the gyros had run down.
I knowingly pulled the second cb.
As it would happen the Observer called a sub contact and a jump request to prosecute.
Forgetting all about the cb off we went with the pilot under check flying the helo. Sometime later the helo, at 200 feet 120kias, took up a mind of its own with great surprise to me!
A masterful display of a/c control recovery by me was quickly followed by a humble apology to the crew who thought the end was nigh!
After the sim was commissioned QHI's were banned from any form of inflight emergency simulation.
E86

[deja vu]

Not all dumb training exercises relate to CB's or system failures. In the late 80's during an AEP session, it was decided that all attendees would go to the adjacent hangar as on of our 737's was undergoing a significant check and the R2 door slide was to be deployed as a routine procedure. So much was made of the deployment onto the hangar floor and then all to go down the slide. Of the 6 pilots and 14 cabin crew there were 4 injuries. Several CC injured their backs and one Captain broke both wrists and was off work for a couple of months. He sued the company successfully for the humiliation of having someone else wipe his backside for many weeks.

I understand an American crew member unnecessarily died after bouncing off a slide from the top deck of a 747 during training.

[mustafagander]

As I recall it, DV, a descent on the slides, all of the buggers on the B747, was required for initial and it was voluntary thereafter. That B747-200 top door slide was a mind bending ride!!

We in QF had a few injuries too. I spent over 35 years on B747 of all types in all seats and did one descent on each slide.

[deja vu]

Originally Posted by mustafagander

As I recall it, DV, a descent on the slides, all of the buggers on the B747, was required for initial and it was voluntary thereafter. That B747-200 top door slide was a mind bending ride!!

We in QF had a few injuries too. I spent over 35 years on B747 of all types in all seats and did one descent on each slide.

Glad you survived unscathed. My point was that going down a slide is unnecessarily introducing the chance of injury when not much is learnt by it really. We, fortunately, were ever asked to go down the escape rope through the cockpit windows.

[RVDT]

And while everyone is contemplating the issue of pulling CB's take a bit of time to review policy on re-setting them.

It's normally in the AFM.

[Checkboard]

Or, if you’re really bored on a long sector, you can play “Circuit Breaker Kerplunk!”

Each person takes turns pulling CBs, until someone pulls a CB which drops out the autopilot, and thus loses the game. You can get a good amount pulled (lights, pitot heat etc) before you really get to a critical one.