C5LOAD From United States of America, joined Sep 2008, 917 posts, RR: 0 Posted (3 years 7 months 3 weeks 4 days 16 hours ago) and read 4696 times:
When we fly and have to do a steep descent, we sometimes deploy the inboard thrust reversers to help slow us down. Do any civilian 4 engine airplanes do this as and emergency descent procedure?
"But this airplane has 4 engines, it's an entirely different kind of flying! Altogether"
T prop From United States of America, joined Apr 2001, 995 posts, RR: 1 Reply 1, posted (3 years 7 months 3 weeks 4 days 16 hours ago) and read 4697 times:
I think DC-8 can on all 4 engines also Trident. Those and some Russian types maybe.
Timz From United States of America, joined Sep 1999, 6465 posts, RR: 8 Reply 2, posted (3 years 7 months 3 weeks 4 days 16 hours ago) and read 4665 times:
Many? Most? All? DC-8s were allowed to use full reverse on #2 and #3-- and not just for emergency, supposedly.
Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 3, posted (3 years 7 months 3 weeks 4 days 15 hours ago) and read 4649 times:
Quoting Timz (Reply 2): Many? Most? All? DC-8s were allowed to use full reverse on #2 and #3-- and not just for emergency, supposedly.
A few can do it, but they tend to be older designs. I'm not aware of any large Western jet since the 80's that can do it. Can't speak for the Russian designs...
L-188 From United States of America, joined Jul 1999, 29350 posts, RR: 62 Reply 4, posted (3 years 7 months 3 weeks 4 days 12 hours ago) and read 4612 times:
ImperialEagle From United States of America, joined Jan 2006, 1230 posts, RR: 14 Reply 6, posted (3 years 7 months 3 weeks 4 days 5 hours ago) and read 4521 times:
quote=C5LOAD,reply=0]When we fly and have to do a steep descent, we sometimes deploy the inboard thrust reversers [/quote]
Are you speaking specifically about the C-5?
Interesting. I wonder what other high-bypass equipped military aircraft also have this capability?
I do not know whether the CFM equipped -8's have this capability.
The P&W -8's certainly use reverse thrust inflight. It was used often on the standard-bodied
-8's and is very effective.
"If everything seems under control, you're just not going fast enough!"
71Zulu From United States of America, joined Aug 2006, 2735 posts, RR: 0 Reply 9, posted (3 years 7 months 3 weeks 4 days 2 hours ago) and read 4443 times:
Concorde could use thrust reversers on #2 and #3 in flight for descents as well...
Dispatchguy From United States of America, joined Jan 2006, 1185 posts, RR: 2 Reply 10, posted (3 years 7 months 3 weeks 4 days ago) and read 4386 times:
Only the older birds could do this, most civilian airliner flight manuals that I have seen have a specific prohibition against deploying a T/R inflight; and, due to system logic, its a near impossibility as you need weight on wheels to be able to close the interlock to deploy a T/R.
Lauda Air lost a B767 climbing out from Asia when his T/R deployed inflight back in 1991 or 1992
PGNCS From United States of America, joined Apr 2007, 2511 posts, RR: 45 Reply 11, posted (3 years 7 months 3 weeks 4 days ago) and read 4379 times:
Quoting Dispatchguy (Reply 10): Only the older birds could do this, most civilian airliner flight manuals that I have seen have a specific prohibition against deploying a T/R inflight; and, due to system logic, its a near impossibility as you need weight on wheels to be able to close the interlock to deploy a T/R.
Lauda Air lost a B767 climbing out from Asia when his T/R deployed inflight back in 1991 or 1992
Good point about the Lauda accident.
All airliner types I have flown (727, 737, 744, 757, 767, DC-9/MD-80/MD-90, L-1011, A-320 family) have been prohibited from inflight reverser use, although as several have pointed out there are types capable and authorized to use inflight reverse. As you mentioned, most aircraft have interlocks that need weight on wheels (i.e. the aircraft needs to be on the ground) to deploy reversers, but some aircraft do not, relying on the intelligence of the pilots not to use the reversers in the air (e.g. DC-9); in my experience it has never been an issue either way.
C5LOAD From United States of America, joined Sep 2008, 917 posts, RR: 0 Reply 12, posted (3 years 7 months 3 weeks 3 days 20 hours ago) and read 4296 times:
Quoting PGNCS (Reply 11): All airliner types I have flown (727, 737, 744, 757, 767, DC-9/MD-80/MD-90, L-1011, A-320 family) have been prohibited from inflight reverser use
Usually T/R usage would only be reserved for 4 engine airplanes that way you have symmetrical thrust on the outboards. Three-engine airplanes could maybe get away with it by deploying the no.2 that way you still have even thrust.
"But this airplane has 4 engines, it's an entirely different kind of flying! Altogether"
JETPILOT From United States of America, joined May 1999, 3130 posts, RR: 32 Reply 13, posted (3 years 7 months 3 weeks 3 days 19 hours ago) and read 4258 times:
The DC8 can reverse thrust in flight up to MCT on engines # 2/3. You can get idle reverse thrust on engines #1/4 when the gear is down. I used reverse thrust in flight once and the engine felt like they were going to rip off.
PGNCS From United States of America, joined Apr 2007, 2511 posts, RR: 45 Reply 14, posted (3 years 7 months 3 weeks 3 days 19 hours ago) and read 4258 times:
Quoting PGNCS (Reply 11):
All airliner types I have flown (727, 737, 744, 757, 767, DC-9/MD-80/MD-90, L-1011, A-320 family) have been prohibited from inflight reverser use
Usually T/R usage would only be reserved for 4 engine airplanes that way you have symmetrical thrust on the outboards. Three-engine airplanes could maybe get away with it by deploying the no.2 that way you still have even thrust.
What are you talking about? ALL of the aircraft I mentioned have reverse thrust on all engines. None, including the 747-400, is approved for inflight reversing; all are approved to use the reversers on the ground to slow the aircraft during landing (or RTO).
C5LOAD From United States of America, joined Sep 2008, 917 posts, RR: 0 Reply 15, posted (3 years 7 months 3 weeks 3 days 18 hours ago) and read 4244 times:
Quoting PGNCS (Reply 14): What are you talking about? ALL of the aircraft I mentioned have reverse thrust on all engines. None, including the 747-400, is approved for inflight reversing; all are approved to use the reversers on the ground to slow the aircraft during landing (or RTO).
Yes, I know all of the airplanes you mentioned have reverse thrust capabilities on the ground, but I am talking about using them in the air. Like I said, with a two-engine jet, you obviously can't use them inflight. But a 4-engine airplane, you could use them in-flight to slow yourself down in a steep or emergency descent. When you deploy them, just the drag helps slow you down. You obviously don't spool them up in reverse.
"But this airplane has 4 engines, it's an entirely different kind of flying! Altogether"
Viscount724 From Switzerland, joined Oct 2006, 21460 posts, RR: 24 Reply 16, posted (3 years 7 months 3 weeks 3 days 18 hours ago) and read 4236 times:
Also the Tu-154, however I believe the Tu-154 and IL-62 only use reversers very close to the ground, unlike the DC-8. If memory correct, the IL-62 only has reversers on the outboard engines, and the Tu-154 only on engines 1 and 3.
PGNCS From United States of America, joined Apr 2007, 2511 posts, RR: 45 Reply 17, posted (3 years 7 months 3 weeks 3 days 17 hours ago) and read 4225 times:
Quoting C5LOAD (Reply 15): Quoting PGNCS (Reply 14):
What are you talking about? ALL of the aircraft I mentioned have reverse thrust on all engines. None, including the 747-400, is approved for inflight reversing; all are approved to use the reversers on the ground to slow the aircraft during landing (or RTO).
Yes, I know all of the airplanes you mentioned have reverse thrust capabilities on the ground, but I am talking about using them in the air. Like I said, with a two-engine jet, you obviously can't use them inflight. But a 4-engine airplane, you could use them in-flight to slow yourself down in a steep or emergency descent. When you deploy them, just the drag helps slow you down. You obviously don't spool them up in reverse.
But that's not what you said in your reply 12. You said "Usually T/R usage would only be reserved for 4 engine airplanes that way you have symmetrical thrust on the outboards. Three-engine airplanes could maybe get away with it by deploying the no.2 that way you still have even thrust."
The Trident could use inflight reverse; and evidently Concorde and the DC-8 could use inflight reverse on the #2 and 3 engines. I have not flown any of those three aircraft, so I have no firsthand knowledge of the operational limitations associated with them. What I do know is that regardless of which of these aircraft we are discussing, symmetrical thrust is possible in either forward of reverse thrust. It is, as I correctly pointed out, not permitted on any of the airliner types I have flown including the 4-engined 747-400. Most of the aircraft I mentioned have interlocks that prevent inflight reverse; some don't.
ImperialEagle From United States of America, joined Jan 2006, 1230 posts, RR: 14 Reply 18, posted (3 years 7 months 3 weeks 3 days 15 hours ago) and read 4189 times:
Quoting JETPILOT (Reply 13): engine felt like they were going to rip off.
Ah, but the -8 is a tough old bird.
The only time I experienced in-flight reverse thrust on a stretched -8 was a -61 of UA's on a flight from Denver to Reno. We dove in over the Truckies with the inboards roaring.
It was very common to use reverse thrust on the standard-bodied -8's. If ATC pulled a fast one on you, you could loose altitude and/or speed in a hurry. It was always very dramatic.
I have fond memories of threading the eye of the needle in a -51 series, diving through afternoon thunderstorms on the way into MCO. Awesome!
"If everything seems under control, you're just not going fast enough!"
JETPILOT From United States of America, joined May 1999, 3130 posts, RR: 32 Reply 19, posted (3 years 7 months 3 weeks 2 days 9 hours ago) and read 3986 times:
One of the -8's in our fleet was an old UA -61. Maybe it was the same plane. Our company for some reason prohibited revrse thrust in flight. I never got an explanation as to why. But I had to do it just once. Captains discretion.... you know the deal. Nothing as tough as the DC8!
Bellerophon From United Kingdom, joined May 2002, 574 posts, RR: 60 Reply 20, posted (3 years 7 months 3 weeks 2 days 1 hour ago) and read 3918 times:
C5LOAD
...Three-engine airplanes could maybe get away with it by deploying the no.2 that way you still have even thrust...
On a three-engined jet aircraft I flew (HS121) - which was approved for the use of reverse thrust in the air - there was no thrust reverser fitted to No.2 engine, so it would have been rather hard to have used it in the manner you suggest.
Reverse thrust was fitted only on Nos. 1 & 3, and could be used on the ground or in the air, on either or both engines, subject to various operational limitations.
On a more general note, having also flown a four-engined jet aircraft on which reverse thrust in the air was permitted, allow me to say this, about both types:
* The use of reverse thrust in the air, on only one engine, if necessary, was permitted.
* There were several operational limitations on the use of reverse thrust in the air.
* These limitations sought to guard against the achieving or maintaining of very high rates-of-descent when near the ground.
* These limitations sought to give the pilot adequate time to shut down an engine should one fail to come out of reverse thrust, when commanded, in the air.
* The most passenger friendly way of using reverse thrust in the air was to use it to decelerate as well as descend, that way a relatively level pitch attitude / cabin floor could be maintained.
On both types, the principal area one had to be very careful about, when using reverse thrust in the air, was to allow oneself sufficient time and height above the desired level-off altitude to cancel reverse thrust, reduce the RoD and then level off without pulling 4g !
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