First - e6bflyer has flown 4 engine aircraft and I haven't. Plus, he speaks from the military perspective while I speak from a civilian pilot perspective. In the civilian world, you have the aircraft flight manual, the company's operating procedures and the Minimum Equipment List MEL). The MEL tells you what you can knowingly fly with that is inop and what adjustments you have to make to do so. The aircraft manual and company ops manual both tell you what to do if something becomes inop while in flight. I have these manuals for the 737, 727, DC-10, CE-500 Citation and DHC-6 Twin Otter. In all cases, the MEL allows you to fly and use the good TRs when you have a TR inop as long as you make the appropriate adjustments to your performance calculations and have adequate runway for the adjusted numbers. Inflight failures normally allow the use of remaining TRs also. I have no idea what the Navy NATOPS and maintenance manuals allow.
The Citation with the tail/fuselage mounted engines, does not have as too much asymmetrical thrust single engine and is very manageable. I've actually done V1 cuts in training in the actual aircraft as well as many, many single engine events in the sim. No problem with using a single TR.
The 737 I've only done single engine stuff in the sim. With the wing mounted engines, it has significant asymmetrical thrust SE. We still used the TR on the good engine.
DHC-6 Twin Otter (turboprop). You can fly with the reverse thrust (beta) inop and you can use the operating engine reverse if required. If you have Hertzell props, you are limited to the amount of reverse thrust you can use 25 lbs torque versus 45 lbs normally). If you have the McCauley props, there are no limits. Hertzell props have significantly more drag when not feathered and significantly more reverse thrust at higher power. They are set for STOL operations/climb efficiency where the McCauleys are set for cruise efficiency. (This has to do with the specific blade angle at the various stops/settings - 100%, 80%, idle, etc.)
727 (3 engines). I've done 2 and 1 engine work in the sim and had an actual 2 engine landing in the plane. Of course, in the sim (and real world) it is never the center engine that goes out. It has the same asymmetrical thrust feel as the 737 if you lose a wing engine. It has even more asymmetrical thrust (at least in the sim) if you lose both a wing and the center engine. In all cases, the procedures still call for using the remaining TRs on landing.
I flew the DC-10 as an FE but we always got stick time in the sim. Same as the 727 for asymmetrical thrust and inop TRs. I bring this one up because not only do the procedures for a MELed TR say to use the remaining TRs, but the EPs actually have you pulling circuit breakers to disable the inop engine TRs. Now the TR does not operate on the dead engine if you move its power lever. The EP directs you to move the power level as if it is operating (i.e. move all 3 TR power levers). The intent is that you get full use of the remaining TRs and don't inadvertently not use a good one because you were avoiding using the bad one.
On a 4 engine aircraft like the 707 or 747, I can see where the losing a TR on an outboard engine might cause even more asymmetrical thrust due to the long arm. But I seem to recall P-3 pilots using reverse on landing when we were 3 engine. Also, I have a friend that flies 747s for Atlas and she says they use all available TRs on landing.
Another thing to chew on. If you lose an engine on your takeoff roll prior to V1, the pilot that observes it will call out engine failure and an abort will be initiated. On most aircraft I've flown, the abort is basically power idle, reverse thrust, spoilers and brakes. You treat the aircraft if all engines are working and don't try and figure out which power lever to use or not to use. You only have so much time and runway to stop. This is especially true if you were close to V1 when the abort was initiated.
Remember, transport aircraft are heavy. They have a lot of weight, speed and momentum on landing. While they can be stopped just using brakes, it takes a lot of brake to do that. This means the breaks get HOT quickly. Hot brakes lead to many other problems. Also, the stopping distances increase significantly when not using the TRs. Some TR is better than no TR. Even just deploying a TR with minimal thrust reduces distances and necessary braking.
I can agree with e6bflyer's wild ride comment. There is a difference between knowingly using asymmetrical TRs and inadvertently using asymmetrical TRs. However, whenever I use a TR, I am ready for it to fail as I had it happen one more than one occasion while flying the mighty Twin Otter. A Twin Otter with Hertzell props has more asymmetrical thrust both when you lose and engine and when you reverse only one engine then any plane I've ever flown. Definitely manageable but an e-ticket ride for the unprepared.
The Citation with the tail/fuselage mounted engines, does not have as too much asymmetrical thrust single engine and is very manageable. I've actually done V1 cuts in training in the actual aircraft as well as many, many single engine events in the sim. No problem with using a single TR.
The 737 I've only done single engine stuff in the sim. With the wing mounted engines, it has significant asymmetrical thrust SE. We still used the TR on the good engine.
DHC-6 Twin Otter (turboprop). You can fly with the reverse thrust (beta) inop and you can use the operating engine reverse if required. If you have Hertzell props, you are limited to the amount of reverse thrust you can use 25 lbs torque versus 45 lbs normally). If you have the McCauley props, there are no limits. Hertzell props have significantly more drag when not feathered and significantly more reverse thrust at higher power. They are set for STOL operations/climb efficiency where the McCauleys are set for cruise efficiency. (This has to do with the specific blade angle at the various stops/settings - 100%, 80%, idle, etc.)
727 (3 engines). I've done 2 and 1 engine work in the sim and had an actual 2 engine landing in the plane. Of course, in the sim (and real world) it is never the center engine that goes out. It has the same asymmetrical thrust feel as the 737 if you lose a wing engine. It has even more asymmetrical thrust (at least in the sim) if you lose both a wing and the center engine. In all cases, the procedures still call for using the remaining TRs on landing.
I flew the DC-10 as an FE but we always got stick time in the sim. Same as the 727 for asymmetrical thrust and inop TRs. I bring this one up because not only do the procedures for a MELed TR say to use the remaining TRs, but the EPs actually have you pulling circuit breakers to disable the inop engine TRs. Now the TR does not operate on the dead engine if you move its power lever. The EP directs you to move the power level as if it is operating (i.e. move all 3 TR power levers). The intent is that you get full use of the remaining TRs and don't inadvertently not use a good one because you were avoiding using the bad one.
On a 4 engine aircraft like the 707 or 747, I can see where the losing a TR on an outboard engine might cause even more asymmetrical thrust due to the long arm. But I seem to recall P-3 pilots using reverse on landing when we were 3 engine. Also, I have a friend that flies 747s for Atlas and she says they use all available TRs on landing.
Another thing to chew on. If you lose an engine on your takeoff roll prior to V1, the pilot that observes it will call out engine failure and an abort will be initiated. On most aircraft I've flown, the abort is basically power idle, reverse thrust, spoilers and brakes. You treat the aircraft if all engines are working and don't try and figure out which power lever to use or not to use. You only have so much time and runway to stop. This is especially true if you were close to V1 when the abort was initiated.
Remember, transport aircraft are heavy. They have a lot of weight, speed and momentum on landing. While they can be stopped just using brakes, it takes a lot of brake to do that. This means the breaks get HOT quickly. Hot brakes lead to many other problems. Also, the stopping distances increase significantly when not using the TRs. Some TR is better than no TR. Even just deploying a TR with minimal thrust reduces distances and necessary braking.
I can agree with e6bflyer's wild ride comment. There is a difference between knowingly using asymmetrical TRs and inadvertently using asymmetrical TRs. However, whenever I use a TR, I am ready for it to fail as I had it happen one more than one occasion while flying the mighty Twin Otter. A Twin Otter with Hertzell props has more asymmetrical thrust both when you lose and engine and when you reverse only one engine then any plane I've ever flown. Definitely manageable but an e-ticket ride for the unprepared.
