63
votes
Accepted
Why not just drop an engine on fire?
The current position of regulators like the FAA is that dropping things off of airplanes in flight is a bad thing. Dropping extremely large and heavy things like engines would be extremely bad. This ...
- 73.8k
63
votes
What is a "runaway supercharger"?
The B-17 had General Electric exhaust-gas-driven turbochargers (or more correctly, turbo-superchargers) that had pilot selectable boost levels. A selector dial in the cockpit controlled the operation ...
- 136k
60
votes
Scared of flying in an Airbus A220
Multiple airlines grounded their entire A220 fleet amid engine concerns
Paradoxically, this should make you feel safer, not less safe. The A220 has had zero accidents. Grounding it is not a sign that ...
- 18.2k
51
votes
Accepted
Have there been any incidents caused by an inability to shut down an engine?
Qantas Flight 32
Enroute to Sydney, Engine Number 2 of the A380 disintegrated explosively. The shrapnel of the explosion destroyed many systems, including a hydraulic system, the anti-lock braking ...
- 9,022
40
votes
Accepted
What is a "runaway supercharger"?
The B-17 uses the term "Turbo Supercharger" which refers to just a Turbocharger (As John K points out in the comments, the former is actually the technically correct term). The B-17 had an ...
- 102k
39
votes
Accepted
Why do uncontained engine failures still occur?
One of the absolute requirements of an aircraft turbine engine (usually some sort of turbofan or turboprop) installation is that, in the event of a destructive failure of the engine, the engine ...
- 56.5k
38
votes
Do commercial flights continue with an engine out?
The image looks like four engines running at the same cruise thrust. The wake vortex is blowing the exhaust of the inboard engines down and the exhaust of the outboard engines out and in the ...
- 56.5k
35
votes
Accepted
Does an airplane fly less or more efficiently after a mid-flight engine failure?
In almost all cases, the maximum range is reduced.
This is because the in-operative engine causes substantial drag. In addition, it causes an asymmetric flight condition that requires deflection of ...
- 16.6k
32
votes
Why are all engines identical in typical commercial airplanes?
Engines don't fail, on average. And if they do, it's a very low probability that two engines will fail at the same time.
Modern jet engines are extremely reliable, with failure rates on the order of ...
- 1,523
32
votes
Does a windmilling propeller create more drag than a stopped propeller in an engine out scenario?
I would not follow the advice in the forum. While the reasoning that a windmilling prop does create more drag is sound, I have seen no empirical evidence that says how much it actually translates to ...
- 54.4k
28
votes
Have there been any incidents caused by an inability to shut down an engine?
Cathay Pacific flight 780 on 13 Apr 2010
Fuel contaminated by super absorbent polymer jammed fuel valves caused engine control problems. The aircraft eventually landed with one engine at about 70% N1 ...
- 56.5k
27
votes
Accepted
Is turning off engines before landing "Normal"?
There's virtually no chance of the pilot deliberately switching off all 4 engines, and even less chance of all 4 engines failing at the same time. It's not entirely impossible for it to happen, but it ...
- 10.4k
27
votes
Accepted
Is there any legitimate reason for adding momentary power when descending at idle with full carburettor heat on?
straight out of the Airplane Flying Handbook, pp 9-4
Operating the engine at idle speed for any prolonged period
during the glide may result in excessive engine cooling, spark
plug fouling, ...
- 75k
26
votes
Could an airliner with only one functioning engine recover from a stall?
Yes, but the challenge is managing the asymmetric thrust effects when applying power during the stall recovery.
Pilots are trained in the sim for two stall (actually, just stick shaker onset) ...
- 136k
26
votes
Accepted
What is the minimum altitude needed to return to the takeoff airport in a 737 after dual engine failure?
Most modern airliners have L/Ds of 18 to 22:1 (sorry I couldn't find a direct reference). So from one nautical mile, 6076 ft, in the air you can glide around 18 to 22 nm in still air.
Departure climb ...
- 136k
25
votes
Accepted
Are jet engines designed in a way to make an explosion result in the least damage possible?
The most (kinetic) energy is in the fan and turbine blades and disc. The engine is enclosed in a containment chamber whose purpose it is to protect the rest of the airplane from shrapnel in case of a ...
- 6,166
24
votes
Accepted
Why are all engines identical in typical commercial airplanes?
In IT more hardware is redundancy, but in aviation a liability
Short answer
In IT, having redundancy and diversity is low cost and no liability, but high gains in service reliability.
In aviation, ...
- 2,387
23
votes
Could an airliner with only one functioning engine recover from a stall?
A stall recovery doesn't require engines (although they help, especially if altitude is an issue). To recover from a stall, you need to lower the angle of attack. You can do this by lowering the nose ...
- 36.2k
22
votes
Accepted
How fast does cabin air pressure leak after a total engine failure?
The valves will not be able to maintain cabin pressure until the plane descends to 10,000 feet at best glide speed. The oxygen masks will deploy before then.
At least that was the case for Air ...
- 438
22
votes
Why are all engines identical in typical commercial airplanes?
Maintenance costs are a big deal. Maintenance costs across multiple engine types for a fleet of the same airplane would be a big deal - training, parts, etc. Worldwide weather tracking & ...
- 8,795
22
votes
Accepted
In an engine failure, should I expect less range than with the engine in idle?
Yes to some degree. It depends on the idle rpm, prop pitch, engine compression and your gliding speed, but if the engine is off but windmilling, there is substantial drag from the energy needed to ...
- 136k
22
votes
What happens when a helicopter loses the engine and autorotation is not initiated?
If you don't lower collective, the blades slow down and stall and the machine becomes a falling rock, with the rotor eventually slowing to a stop if there is enough time to ground contact. Yaw will ...
- 136k
21
votes
Accepted
What could cause both engines on a 737-200 to fail at nearly the same time?
Generally, without knowing the details of this accident, dual engine failures are typically caused by one of the following:
fuel events
exhaustion
starvation (e.g. due to iced fuel filters)
...
- 84.5k
21
votes
What is the minimum altitude needed to return to the takeoff airport in a 737 after dual engine failure?
First, the actual "impossible turn possible" altitude number is going to vary dramatically by factors such as hot, high, heavy, wind, how wind interacts with your departure path, and ...
21
votes
Scared of flying in an Airbus A220
How will you be getting to the airport? Flying in an airliner with a relatively poor safety record is still orders of magnitude safer than traveling by car, for example. –
Frog
Driving in a car –
...
- 16.4k
20
votes
Why not just drop an engine on fire?
The fact that the modern aircraft could fly with one engine out does not mean that the offending engine should be dropped. It is better to have it in the aircraft rather than risk the engine taking ...
- 101k
20
votes
Could an airliner with only one functioning engine recover from a stall?
With enough height, any aircraft can recover from a stall without any engine power required. In fact, for under-wing engined aircraft like the 787, it is sometimes necessary to reduce the thrust, ...
- 14.6k
19
votes
In which direction should a turn-back be made after an engine failure on a multi engined airplane after take off?
That depends on a lot of factors. Are you declaring an emergency? What altitude are you at what speed are you at when this happens etc? What kind of aircraft are you flying? Does it have enough ...
- 75k
19
votes
Have there been any incidents caused by an inability to shut down an engine?
Etihad Airbus A340-600
This famous crash happened on the acceptance engine run-up test. The causes were unrelated to engine problems, but after the crash, due to damages, two engines couldn't be shut ...
- 9,123
Only top scored, non community-wiki answers of a minimum length are eligible