United960
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AZ 747-100 Pic; Engine Failure?

Mon Oct 04, 2010 5:43 am


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Photo © Alberto Storti



I saw this great photo of an AZ 747-143 taking off from Milan in 1974. But I am struck by the technical details. Has this aircraft just had an engine failure? Note that the number 1 engine's sucker plates are closed, and that there is significant right rudder deflection even though the aircraft is banked for a left turn. The photo appears to have been shot from the ground - indicating that it was taken right after rotation. Is there any other explanation I am blanking on here for why the rudder would be deflected so significantly in a way that would appear to knock the airplane out of coordinated flight?
 
B595
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RE: AZ 747-100 Pic; Engine Failure?

Mon Oct 04, 2010 6:11 am

It could also have been a three-engine ferry flight, rather than an engine failure.

If it's not an engine failure or a three-engine ferry, then the rudder might be explained by the aircraft beginning its roll-out to the right. However, like you say it's rather strong right-rudder, and right-rudder for the roll-out should be accompanied by down-aileron on the left wing and I don't see that.
 
mrskyguy
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RE: AZ 747-100 Pic; Engine Failure?

Mon Oct 04, 2010 6:14 am

Excellent photo observation. Do the doors close automatically upon a loss of thrust? (eg. bleed air controlled?)

I see about maybe 10 degrees or less of right deflection in that massive barndoor rudder.
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andrewuber
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RE: AZ 747-100 Pic; Engine Failure?

Mon Oct 04, 2010 6:28 am

Another pic of this same exact aircraft with it's #4 engine's "sucker plates" closed while the inboard engines are open (and it has a bit of left rudder going on).


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What's up with that??
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mrskyguy
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RE: AZ 747-100 Pic; Engine Failure?

Mon Oct 04, 2010 6:30 am

Thrust controlled? Now that I'm thinking back, I seem to recall the doors positioned themselves based upon the demand for air within these engines.. but I would imagine all 4 would be set at or close to the same thrust? Perhaps it has something to do with the bleed air demand at that phase of flight?
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andrewuber
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RE: AZ 747-100 Pic; Engine Failure?

Mon Oct 04, 2010 6:34 am

In all other images of this aircraft - several in flight and several taxiing, the doors are closed.
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United960
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RE: AZ 747-100 Pic; Engine Failure?

Mon Oct 04, 2010 2:26 pm

Thanks for all the replies. It seems like the question is if it is possible for the pilot to manually close the sucker plates at high thrust settings. I don't know why the pilot would want to do that, as it would reduce engine air flow. But perhaps the sucker plates could be locked out if inop? Andrewuber, excellent job finding a comparable pic with the same differential sucker plate configuration. But my only question there is that in your pic, the aircraft is on approach - so the engines could be at intermediate power settings - and even at differential thrust settings (unlikely, but the throttle cables were often pretty uneven on some of the older birds). But in my original picture, the engines should all be at max blast, given that it was taken right after rotation. Any other ideas?
 
Vmcavmcg
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RE: AZ 747-100 Pic; Engine Failure?

Mon Oct 04, 2010 2:41 pm

Quoting United960 (Reply 6):
Thanks for all the replies. It seems like the question is if it is possible for the pilot to manually close the sucker plates at high thrust settings.

No, the bypass doors are automatic and open to ensure extra airflow into the fan section.

Quoting United960 (Reply 6):
But in my original picture, the engines should all be at max blast, given that it was taken right after rotation. Any other ideas?

Not true. Depending on the TOW, the power could have been at a reduced thrust/assumed temperature setting which could be as much as 25% below the full rated takeoff thrust. So, with that in mind, there could have been a mis-rigged cable that would have resulted in an EPR just below what is required for the bypass doors to open.
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United960
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RE: AZ 747-100 Pic; Engine Failure?

Mon Oct 04, 2010 5:22 pm

Quoting Vmcavmcg (Reply 7):
Not true. Depending on the TOW, the power could have been at a reduced thrust/assumed temperature setting which could be as much as 25% below the full rated takeoff thrust. So, with that in mind, there could have been a mis-rigged cable that would have resulted in an EPR just below what is required for the bypass doors to open.

Excellent. That is exactly what I wanted to know. The only other question, then, is about the rudder deflection. I understand from my own experience flying general aviation aircraft that the pilot would be turning the control wheel to the right to roll the aircraft out of that left turn, resulting in the downward deflection of the all-speed and low-speed ailerons on the left wing. But on the 747, would the rudder input needed to roll the aircraft back to straight be that significant? In other words, I guess I am surprised that in normal ops you would have that significant of an opposite-rudder input just to roll the airplane back to straight. The way it looks, it seems like the airplane would be out of coordinated flight. But I have never flown anything anywhere near that big, so I have no idea what the low-speed characteristics are like.
 
tdscanuck
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RE: AZ 747-100 Pic; Engine Failure?

Mon Oct 04, 2010 5:43 pm

Quoting United960 (Reply 8):
But on the 747, would the rudder input needed to roll the aircraft back to straight be that significant?

This may be the yaw damper at work...the 747 was known to wag its tail pretty severely without the yaw damper, suggesting that it needed to make large rudder inputs (especially at low speed).

Tom.
 
b78710
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RE: AZ 747-100 Pic; Engine Failure?

Mon Oct 04, 2010 7:57 pm

747-400 yaw damper/autopilot max authority is 4 or 5 degree's

i assume the classic is the same
 
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747classic
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RE: AZ 747-100 Pic; Engine Failure?

Tue Oct 05, 2010 7:37 pm

Seen the pitch attitude this could be a N-1 training flight, with one engine at idle power, at relative low aircraft weight.
This was quite normal in the seventies (no zero-zero training available at the simulator).
In those days the initial type qualification training was at the simulator. The final part was actual performed on a real aircraft (including simulated N-1 failures after V1 and N-1 approaches.).

Quoting b78710 (Reply 10):
747-400 yaw damper/autopilot max authority is 4 or 5 degree's



On the 747-100/200/300/SP the rudder is not included in the A/P channels.
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Viscount724
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RE: AZ 747-100 Pic; Engine Failure?

Wed Oct 06, 2010 2:01 am

Possibly a training flight simulating an engine failure on takeoff, with the #1 engine reduced to idle thrust?
 
HaveBlue
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RE: AZ 747-100 Pic; Engine Failure?

Wed Oct 06, 2010 3:28 am

Quoting 747classic (Reply 11):
Seen the pitch attitude this could be a N-1 training flight, with one engine at idle power, at relative low aircraft weight.
This was quite normal in the seventies (no zero-zero training available at the simulator).
In those days the initial type qualification training was at the simulator. The final part was actual performed on a real aircraft (including simulated N-1 failures after V1 and N-1 approaches.).

I like this theory the best. Imo the engine is at idle thrust and the strong right rudder is to offset the 'lost' engine, and since this was early into the 747's flight career and as he pointed out (and I would have not thought of myself) the training was done in aircraft, not in sims.

Interesting thread either way.
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CCA
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RE: AZ 747-100 Pic; Engine Failure?

Thu Oct 07, 2010 5:18 am

As others have said, most likely engine out training.
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