"Easy" Electrical failure AAIB report
Keeping Danny in Sandwiches
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"Easy" Electrical failure AAIB report
This is one of the hardest hitting reports that I have seen from the AAIB, directly at both the FAA and Boeing raising serious issues with the electrics on the 737.
A must read.
http://www.aaib.dft.gov.uk/publicati...3v__g_ezyn.cfm
A must read.
http://www.aaib.dft.gov.uk/publicati...3v__g_ezyn.cfm
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Good men
Sounds like the crew used sound airmanship and deduction and made a good decision.
It's on occasions like this, that the brains in the cockpit are far ahead of some techie inspired trouble shooter based on standard expected failures.
FC.
It's on occasions like this, that the brains in the cockpit are far ahead of some techie inspired trouble shooter based on standard expected failures.
FC.
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Very Well Handled!
What a really interesting read. 
The crew used great deduction in mid air to use the alternate cooling fans.
So simple a fix of Stanby pwr to BATT instead of AUTO to bypass the relay. But who would know?
In the heat of the situation as well, for the crew to realise they had no engine fire detection protection is well thought out. 
The question I had was to do with LDG Gear unsafe annunciation and PA/ intercom system? Which I think the report doesn't really deal with.
I suppose that the PA and intercom system is powered by BATT Bus but is there no back up to this? Surely this is an essential system which requires two independent power supplies. Possibly Transfer Bus 1 to Standby Bus? There are two supplies to BATT Bus but with one relay able to shut down the Bus there should really be a backup? Also flt deck door runs on DC but why did this become inop? There was still some DC power from TR'S was there not? Or is this run of BATT Bus as well?
Why was there a Nose Gear Unsafe indication? Is this Also the BATT Bus.
Makes you think when the back up to your power supply problems is the item that fails.
Also there doesn't seem to be an answer to do with Cowl valve indication which is DC powered if I remember right
and why power was restored on G/S capture.
Honestly, a job very well done from Flt Crew in very difficult circumstances.
More investigating is needed.
The crew used great deduction in mid air to use the alternate cooling fans.
So simple a fix of Stanby pwr to BATT instead of AUTO to bypass the relay. But who would know?
In the heat of the situation as well, for the crew to realise they had no engine fire detection protection is well thought out. The question I had was to do with LDG Gear unsafe annunciation and PA/ intercom system? Which I think the report doesn't really deal with.
I suppose that the PA and intercom system is powered by BATT Bus but is there no back up to this? Surely this is an essential system which requires two independent power supplies. Possibly Transfer Bus 1 to Standby Bus? There are two supplies to BATT Bus but with one relay able to shut down the Bus there should really be a backup? Also flt deck door runs on DC but why did this become inop? There was still some DC power from TR'S was there not? Or is this run of BATT Bus as well?
Why was there a Nose Gear Unsafe indication? Is this Also the BATT Bus.
Makes you think when the back up to your power supply problems is the item that fails.
Also there doesn't seem to be an answer to do with Cowl valve indication which is DC powered if I remember right
and why power was restored on G/S capture. Honestly, a job very well done from Flt Crew in very difficult circumstances.
More investigating is needed.
Keeping Danny in Sandwiches
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The scandal is that on another day with another crew there could have been a total loss of attitude information because of the failure of Boeing to provide proper checklist.
The Danish AAIB had made a recommendation in 1997 after a similar incident. The AAIB now have recommended that the FAA require Boeing examine the various electrical systems on their NG 737's and come up with proper proceedures or even system modification.
The Danish AAIB had made a recommendation in 1997 after a similar incident. The AAIB now have recommended that the FAA require Boeing examine the various electrical systems on their NG 737's and come up with proper proceedures or even system modification.
