Hi,
Thanks for the feedback.
All engines fail. Means that. Who cares how, as long as end result is the same.
I was wondering about the definition of engine failure, does engine failure mean voluntary or involuntary engine shutdown, engines flame-out: that’s why I mentioned some causes (related to engines & aircraft, weather, crew or maintenance mistakes,…) that result in engine shutdown. Let say you had birds strike with high EGT, surge and/or vibrations: you may opt to keep engine(s) running to get some thrust with hydraulic/electrical… when you reduce the thrust (engine at idle). So you have engines failures but one or more engines are still running (even though not properly). Other may elect to shutdown engines because of the risk of engine separation and wing damage (torn or missing slat, flap,…) which may cause problem controllability.
Demonstrate it. Not a big prob, actually. Production test flight usually accomplishes this.
I thought they will shutdown one engine at time and restart it again. Do you shutdown all engines at the same time? If so at what altitude?
Explanation. This material deals with the all-engines out case of § 25.671(d). The intent of this rule is to assure that in the event of failure of all engines, the airplane will be controllable and an approach and landing flare possible. This may be done by analysis where the method is considered reliable.
b. Procedures. The airplane should be evaluated to determine that:
(1) It is controllable following the failure of all engines in the climb, cruise, descent, approach, and holding configurations and can be flared to a landing attitude from a reasonable approach speed. The airplane must be controllable when all engines fail in each of the specified configurations and in any specific configuration that is to be selected and maintained following the failure of the engines in accordance with the AFM emergency operating procedures
(2) The effectiveness of the emergency power to drive the airplane control system, whether generated from a windmilling engine or an auxiliary power supply, should be demonstrated in flight.
(3) For airplanes with fully powered or electronic flight control systems, the emergency procedures section of the approved Airplane Flight Manual should contain the appropriate operating procedures and a statement
similar to the following:
"The airplane has a fully powered (or electronic) control system that is dependent upon engine windmill RPM, or an auxiliary power supply, to provide the necessary source of control system power in the event
all engines fail in flight. A minimum airspeed of XXX knots IAS will provide adequate hydraulic or electrical power for airplane controllability in this emergency condition."
“
in any specific configuration” do you think this phrash includes takeoff (or end of take-off and the beginning of climb? If so do you think it is possible to control aircraft in such configuration after all engines failure (let say after birds strike).
I am wondering if the information or guidelines in Advisory Circular are mandatory? Since it is called advisory circular and not regulation.
The reason of this thread is to know your opinions regarding this regulation (issued on 04/01/70) and considering all engines failure incidents/accidents… that occurred in the past.
One may ask what was added to 747-400 incident after flying through volcanic ash? I guess in this incident the crew were able to restart engine(s) (may be one engine?), otherwise they may faced big challenges.
Do you think that APU, RAT, windmilling engines played an important role on the successful ditching (A 320 in Hudson River)?
Volcanis ash or birds strike may affect the windmilling RPM (damaged blades…), also windmilling RPM is reduced on high bypass engines. I am assuming the advisory circular is talking about flight test with shutdown engine and not damaged (intact blades, no sized spool…).
I am also thinking about B 777 (BA) accident after the fuel flow get restricted by ice.
I apologize if this post is too long.
Feedback appreciated
Regards