737NG Complete loss of electrical power.
I did the B777 course in Seattle in 2008 and I recall our Boeing simulator instructor (who was fully qualified on type) telling us that when the 777 electrical fault analysis was done, it was realized that the 777 system redundancy and architecture made it statistically more probable that a 747 could experience a complete electrical loss of power than a 777.
I only have experience of one company’s ETOPS requirements on the NG so it’s not definitive, but we couldn’t dispatch an ETOPS flight unless both engine generators and the APU generator was serviceable. In flight the APU had to be started prior to the ETOPS entry point and if it didn’t start or one of the engine driven generators failed prior to the entry point then we had to re-route to ensure we remained within one hour of a suitable airfield. I would imagine that would apply to most ETOPS aircraft unless they have a RAT that can provide sufficient power if one of the other sources fails.
I remember a different kind of incident though on a classic, where the battery would not charge.
:As the Boeing 737-300 aircraft was on approach to its destination, the pilots were confronted with substantial thunderstorm activity visible ahead and on their onboard weather radar.[2] They attempted to fly between two intense weather cells visible on their radar. They later entered a thunderstorm containing heavy rain and hail. About 90 seconds later, as the aircraft was descending through 19,000 ft (5,800 m), both CFM International CFM56 engines experienced a flameout, which resulted in the loss of all generated electrical power.
Both engines were set at their flight-idle power setting before flameout occurred. The crew tried unsuccessfully to restart the engines two or three times. They then tried but failed to start the auxiliary power unit (APU), at which time total electrical power loss occurred. (During the later investigation, the NiCd battery was found to have been in poor condition due to inadequate maintenance procedures.) . As the aircraft descended through the lower layer of clouds at approximately 8,000 ft (2,400 m), the pilots saw the Bengawan Solo River and decided to attempt to ditch in the river with the flaps and gear retracted. The ditch procedure was successful, leaving the aircraft settled down on its belly in the shallow water, with the fuselage, wings and control surfaces largely intact. There was no fire.
The investigation revealed a poorly maintained radome that resulted in a very much reduced range. When the crew tried to start the APU following the double engine flameout due rain ingestion, the battery failed simultaneously which left the crew with loss of all electrics in IMC.
The standby artificial horizon failed due loss of electrical power but what saved the day was the aircraft broke clear of cloud just as the standby AH gave up the ghost and toppled. The ditching at 180 knots was well handled and everyone escaped apart from one unfortunate cabin attendant trapped down the back when the floor collapsed.
Sounds like a good simulator exercise designed to sort the men from the boys! Even the most brutal of simulator instructors would never dream up such an unlikely combination of failures in IMC and heavy turbulence. Yet it happened for real that day.
See full report: https://en.wikipedia.org/wiki/Garuda...ral%20injuries.
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We also don’t operate aircraft that have lost all electrical power maybe 2 hours from land over the sea in bad weather. At least we hope not! If it does happen it’s nice to know where you are.
I beg to differ. The MAX may be over the middle of the Amazon forest without an airport with suitable runway length available under 60 minutes of flight time remaining for navigation.
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Required runway length for the MAX with a loss of all generators scenario. I'm not sure of the reason, but the loss of anti-skid along with the loss of the electric flight/ground spoilers might be the culprit. The numbers are surprisingly large, especially for a wet/good runway.
Going "Wet-Good" changes to 10,800' with Reverse, 14,400' No Reverse. Example of these conditions is Guayaquil (although sea level). Useable landing length approx 8450'
Having a statistically very bad day departing Quito, Ecuador at 175K with a deferred Engine Generator followed by the loss of the APU and remaining Generator? (low prob of course), Dry runway, 12,500' (1000 cushion), Wet-Good, 15,100', both with Reverse. No Reverse Dry? 14,200', Quito runway length is 13,445'. Guayaquil not an option.
My example over the Amazon on a rainy night? My previous equipment of 777,767,757 would involve a Split-S into Manaus and grumble about hotel rooms as I imagine all the Airbus series along with the 787/747. The MAX seems to require more runway than MAO would offer. I don't pretend to be an expert. I don't know what the reason is for the high numbers with that condition. Anti-skid degradation is understandable. There is a loss of spoiler capability as well and maybe a loss of the LAM (Landing Attitude Modifier) spoiler function may have an effect.
Long travel through the proverbial line up of Swiss Cheese holes, but someone usually finds a way eventually.
