Date: 11 Feb 98 04:23:54 From: email@example.com (James Matthew Weber) Organization: Customer of Access One Pty Ltd, Melbourne, Australia References: 1 2 3 4 5
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> One disadvantage of mixed engines is that I suppose all engine-out >performance figures would have to be figured for the worst case, with >one of the larger engines inoperative. This could result in a lower >maximum take-off weight for the same airframe. I doubt this is as much of a problem as it seems to be. In the 1980's Qantas had a 747-100 with 1 x JT9D-3A's, 1 X JT9D-7A , 2 x JT9D-7F. It was a leased aircraft, but there is considerable variation in engine performance there. My recollection is that covers about 40,000 to 48,000 pounds thrust. I don't know what impact that had on procedures. I imagine it might have made the autothrottles interesting, but QANTAS had so much trouble with P&W autothrottles they disabled them quite early on so that was a non-issue. Given that this was obviously an early 747-100, I doubt it impacted the MGTOW at all. The thing was probably certified for the -3A's. My thoughts anyway.