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View Full Version : MD-11 center engine V1 cuts, is this an issue?


DAL2728
1st May 2006, 22:27
I remember talking to a pilot in DVA where I fly, he's a real world World Airways MD-11 pilot, and he was saying that rejected takeoffs prior to V1 involving the #2 engine cutting out were always the worst, but I really didn't get an explanation.

Is this true, and if so, what about losing the center engine is so dramatic?

barit1
1st May 2006, 22:40
From an earlier thread somewhere in here, it's the pitch-up moment from the loss of #2 (which is well above the centre of mass) - getting the nosewheel back down may be an issue.

JW411
2nd May 2006, 10:30
Can't speak for the MD-11 but if you lost the centre engine on take-off in the DC-10 you had to push forward pretty smartly on the control column to keep the nosewheel on the runway. Otherwise the aircraft would rotate itself.

Xavier Onassis
9th May 2006, 11:34
If you lose a centreline engine, there is no assymetric effect and therefore no swing. As a result, recognition of the failure is more difficult. In performance calculations, it is required that an extra second be allowed between the point of failure and action, in the event of the number 2 deciding to give up for the day. On the L-1011, Lockheed incorporated a separate warning light in the pilot's eyeline to warn of No 2 eng fail to get around the extra sec performance penalty.

barit1
9th May 2006, 13:00
The Cessna 336/337 had a similar situation with the aft engine. (Failure of the front engine is a bit more obvious!)

JW411
9th May 2006, 19:24
I'm surprised to hear that the Cessna 336/337 tried to rotate itself if the rear engine failed on take-off.

I would have thought that both engines were mounted at the same thrust line but I am obviously wrong.

CV880
10th May 2006, 05:53
The L1011 had a No. 2 Eng Fail indicating system; a green ARM light would illuminate on the centre annunciator panel (CAWP) when TO power was set, then No. 2 FAIL lights on the glareshield would illuminate following a set loss of rpm while in ground mode (forget which shaft was monitored but think it was N2). There was a performance penalty, probably due to recognition time, if dispatching with the No. 2 Fail system inop.
I seem to recall the DC10 also had an engine failure indicating system which annunciated ANY engine loss of power on TO (not just No. 2).
Another interesting related subject is the affect of No. 2 engine reverse thrust on the DC10/L1011 especially if you configured the cascade vanes incorrectly on the L1011. The DC10 had mechanical/electrical inhibits in the No. 2 reverser controls to either prevent selecting reverse until the nose gear was compressed or to prevent opening No. 2 up in reverse until the nose gear was compressed (former applied to older DC10's, later build standard allowed reverse idle to be selected on all 3 together but No. 2 could not be moved passed the interlock until the nose gear was down).
I have seen L1011's get the nose gear airborne in spite of full stick forward pressure after nose gear touchdown as No. 2 wound up in reverse due to misconfigured cascade vanes

barit1
10th May 2006, 13:53
I'm surprised to hear that the Cessna 336/337 tried to rotate itself if the rear engine failed on take-off.
I would have thought that both engines were mounted at the same thrust line but I am obviously wrong.

It's not that the airplane would self-rotate - it's just that failure of the aft engine wasn't real obvious to the driver, and unless he cross-checked his gages, he might try to TO with the aft engine stopped. :oh:

I think there's been a few accidents due to this.

In fact, the aft engine has a thrust line a foot or two higher than the front, so it's possible that aft engine failure might cause some pitch-up. Can't say for sure.

con-pilot
10th May 2006, 19:46
The same type of engine failure system is on the Falcon 50 and 900 in case of #2 engine failure.

Ignition Override
11th May 2006, 06:45
As for center engine loss of compressor or turbine blades in DC-10s, it took quite a disaster for the engineers to modify the clustered hydraulic lines, because of the location near the center engine.

barit1
11th May 2006, 17:27
As for center engine loss of compressor or turbine blades in DC-10s, it took quite a disaster for the engineers to modify the clustered hydraulic lines, because of the location near the center engine.

Or the L-1011 aft pressure bulkhead's proximity to the #2 fan rotor - when the thrust bearing no longer holds it in place. :oh:

glhcarl
11th May 2006, 18:13
Or the L-1011 aft pressure bulkhead's proximity to the #2 fan rotor - when the thrust bearing no longer holds it in place. :oh:
Its over 12 feet from the aft pressure bulkhead to the #2 engine fan on an L-1011.

barit1
11th May 2006, 21:44
Its over 12 feet ...

'twas just enough in this (http://aviation-safety.net/database/record.php?id=19810922-0&lang=en) case. The #2 fan rotor assembly nearly entered the aft loos. :eek:

glhcarl
12th May 2006, 02:09
'twas just enough in this (http://aviation-safety.net/database/record.php?id=19810922-0&lang=en) case. The #2 fan rotor assembly nearly entered the aft loos. :eek:
The fan never hit the Aft Pressure Bulkhead, it worked its way up the S-Duct and exited through the side of the fuselage. The S-Duct was holed by shrapnel, and seeing as it is only 0.040" of an an inch thick (with 0.040" doublers), it does not take a lot to hole it.

tinpis
12th May 2006, 02:31
Cessna 337 didnt have a V1
If rear failed the front engine pretty well allowed you to select where you would crash.