Originally Posted by
BraceBrace
So a full and non-recoverable loss of all AC power generation is really lottery level stuff.
Maybe, maybe not. As I mentioned, I don't know the exact numbers, but there is another consideration, the numbers across the civil aviation fleet might not be well known since a loss of Engine and APU generators has been a non-event in most aircraft types. Lottery level failures would probably apply to the 4 and 3 engine types where one has 4-5 Generators and maybe RAT backup. On the 2 engine types, the older 767/757 ER aircraft were equipped with hydraulic generator backup, providing 4 sources of flight display redundancy. On 2 engine Airbus, my understanding is the the RAT will provide the same.
The 737NG/MAX have reduced the number of electrical backups to 3. What I don't pretend to know is the MTB failure design specs on the NG/MAX. Have they improved significantly over the years? Hopefully yes. One still has to admit that no matter how good the odds, the aircraft is unflyable IFR after the IFSD battery dies after a loss of all generators. On other civil types with electric RAT options, not so much. The MAX also requires significant runway length in that scenario.
The Lottery jackpots for 3 numbers are significantly less than those for 4 or 5 numbers
