Just a few "simple" questions about 767 engine trimming....
1. Should both engines on a GE-powered 767 run at exactly the same N1 in (normal) flight when being controlled by the Thrust Management Computer? (i.e. down to the last decimal point)... or is there generally a split?
2. If there is an N1 split, are FADEC engines any closer (rpm wise) than non-FADEC? (or does EEC engine trimming produce the same N1 anyway?). By FADEC, I mean no steel cables running from the cockpit to the engines.
3. When trimming is applied to compensate for bleed air demands, what are the EEC's(?) looking at? Pressures sensed at the engine? Bleed duct pressures? Valve positions? Cockpit switch positions? All of the above?
3. If bleed requirements are assessed at the engine.... does the EEC on, say the left engine, trim only the left engine...
or does the TMC look at the bleed requirements for both engines, average them and then set N1's on both engines to the same value. If the Bleed Isolation Valves are normally closed for flight, presumably this would mean that each engine would have a different bleed demand placed on it(?).
Thanks in advance.
Cheers.. .Q.
[ 28 February 2002: Message edited by: QAVION ]</p>