United 811 Door Blowout Revisited (N1 and Fuel Flow)
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United 811 Door Blowout Revisited (N1 and Fuel Flow)
I was reading the CVR for United 811; that's the flight from Honolulu to Sydney in the 747 where the door blew out in flight.
Here's an exerpt from the CVR:
1641 C NO FUEL FLOW NOW FUEL FLOW ON NUMBER AH FOUR ENGINE
1644 F HOW CAN WE HAVE NO FUEL FLOW IF WE GOT N1 AND EGT
Good question from the FE. If I'm reading the first statement correctly, how can you have EGT with no fuel flow?
Here's an exerpt from the CVR:
1641 C NO FUEL FLOW NOW FUEL FLOW ON NUMBER AH FOUR ENGINE
1644 F HOW CAN WE HAVE NO FUEL FLOW IF WE GOT N1 AND EGT
Good question from the FE. If I'm reading the first statement correctly, how can you have EGT with no fuel flow?
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Several possibilities spring to mind.
Faulty indication...
The engine has flamed out but the FO didn't notice that the EGT is slowly decreasing...
The engine has flamed out but there's a hydraulic leak somewhere which has ignited in the vicinity of the EGT probe...
Faulty indication...
The engine has flamed out but the FO didn't notice that the EGT is slowly decreasing...
The engine has flamed out but there's a hydraulic leak somewhere which has ignited in the vicinity of the EGT probe...
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Just a couple of points there is still fuel flow during a flame out other wise it wouldn't be a flame out, and there is no way for hydraulic fluid to come into contact with the EGT probes as there is no way for the fluid to get into the core unless it goes down the inlet.
I'm thinking Indication like Captain stable or the engine is stalling/surging and the fuel control unit is having a brain fart associated with that, which results in the erroneous FF indication as FF is measured after the FCU.
I'm thinking Indication like Captain stable or the engine is stalling/surging and the fuel control unit is having a brain fart associated with that, which results in the erroneous FF indication as FF is measured after the FCU.
Personally, I would expect a few wires to be damaged in that particular incident. So, some oddball indications would not be at all out of place.
As a rule, I've always been happy to accept that an engine is OK if I see any 2 of N1, N2, (N3), EGT, F/F. Would you call a failure with only 1 parameter wrong?? I certainly wouldn't!
As a rule, I've always been happy to accept that an engine is OK if I see any 2 of N1, N2, (N3), EGT, F/F. Would you call a failure with only 1 parameter wrong?? I certainly wouldn't!
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You never judge engine status by a single gauge, but rather by a combination and comparison of parameters: N1,N2,(N3 Rolls Royce), TGT/EGT, Fuel flow.
So, just because one guage has gone on vacation, or because its indication is erratic or intermittant, doesn't by itself draw any conclusions or generalizations about engine performance.
So, just because one guage has gone on vacation, or because its indication is erratic or intermittant, doesn't by itself draw any conclusions or generalizations about engine performance.
