Gonzalo From Chile, joined Aug 2005, 1674 posts, RR: 0 Posted (5 months 4 days 9 hours ago) and read 5642 times:
I was doing my usual tour for some of the aviation video channels, and I came across this video of a Tu-154 activating the thrust reverser well before the wheels touched the runway. I had the ( wrong? ) idea about all the commercial / civil aircraft had weight on wheels sensors, to prevent in flight deployment of the T/R ( I remember the case of a Lauda Air Boeing 767 crashed after an uncommanded T/R activation, with a high loss of lives )
Video :
https://www.youtube.com/watch?v=Yq5HLtdGeqE
Is this a characteristic of the Tu 154 ? Or was this particular aircraft on the video under some special condition ( MEL'd, Ferry flight to MX ) ?
Are there any other civilian / pax aircraft type / model that allows this ?
DocLightning From United States of America, joined Nov 2005, 16819 posts, RR: 57 Reply 1, posted (5 months 4 days 9 hours ago) and read 5589 times:
Quoting Gonzalo (Thread starter): Is this a characteristic of the Tu 154 ? Or was this particular aircraft on the video under some special condition ( MEL'd, Ferry flight to MX ) ?
There are a few others. Presumably, the Tu154 locks out the reversers until the engines are at idle, although given that it's a 1960's Russian design, I'm not entirely sure about that.
northstardc4m From Canada, joined Apr 2000, 2804 posts, RR: 40 Reply 2, posted (5 months 4 days 9 hours ago) and read 5574 times:
AIRLINERS.NET CREW CHAT OPERATOR
This was the case on a few jetliners:
DC-8 up to model 61
VC-10
IL-62
some models of Tu-134 and most is not all models of the Tu-154
Not common but if the plane is designed for it...
DC-8s had it only on engines 2 and 3, and some issues causing a couple crashes cause it to be disabled later on.
Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety.
BoeingGuy From United States of America, joined Dec 2010, 2307 posts, RR: 7 Reply 4, posted (5 months 4 days 9 hours ago) and read 5465 times:
Quoting northstardc4m (Reply 2): Not common but if the plane is designed for it...
DC-8s had it only on engines 2 and 3, and some issues causing a couple crashes cause it to be disabled later on.
The DC-8 in flight thrust reversers were intended to be used as speedbrakes. I don't think they were intended for use shortly before touchdown the OP was referring to. I'm not aware of crashed because of it. I experienced as a passenger as late as 1977 and thought I heard that the CFM engines on the -71s and -73 were also designed to used in reverse in flight.
Can you elaborate on the crashes and how in-flight thrust reverse used was disabled on the DC-8s?
migair54 From Spain, joined Jun 2007, 1277 posts, RR: 0 Reply 5, posted (5 months 4 days 9 hours ago) and read 5462 times:
If i´m not mistaken the conconrde also could do to reduce speed, Russian planes as usual have some special features, they fly in somehow a different way from the western planes.
For example, when you see a russian plane taking off, for them getting speed first and then climbing is the procedure, but for western planes altitude is first then speed, if you think a bit in a place with a big clearway and no noise abatement it could be a good practice because in the Lift formula V is Square so increasing speed has a very big effect on lift.
But anyway, I´ve seen few Tu-154 and IL-62 mainly doing that. I think the pilatus porter can also do, but of course that´s not a jetliner.
Quoting northstardc4m (Reply 2): DC-8s had it only on engines 2 and 3, and some issues causing a couple crashes cause it to be disabled later on.
i´m sure the forces generated in the pylon of the engines must have been terrible, they are designed to do let the engine pull the plane forward and not backward.
apparently all 4 engines could do reverse sorry... and I was under the impression that it was actually disabled, though apparently it was just airline policy.
And i'm finding more types:
Trident
Concorde
Tu-144
Jetstar
Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety.
Ah de Havilland.
Now the Trident only had reverse on 1 and 3.
But they were deployed regularly in the descent as speedbrakes.
Then the aircraft could descend very fast. So fast that one Trident, I think it was the 2E did not have passenger oxygen fitted. In case of emergency, engines to idle, select reverse, descend nose down!
BoeingGuy From United States of America, joined Dec 2010, 2307 posts, RR: 7 Reply 10, posted (5 months 4 days 8 hours ago) and read 5036 times:
Quoting Tristarsteve (Reply 9): So fast that one Trident, I think it was the 2E did not have passenger oxygen fitted. In case of emergency, engines to idle, select reverse, descend nose down!
I can't imagine that. It's still like 3 minutes from cruise to 10,000 feet.
longhauler From Canada, joined Mar 2004, 4280 posts, RR: 36 Reply 12, posted (5 months 4 days 6 hours ago) and read 4715 times:
Quoting Tristarsteve (Reply 9): So fast that one Trident, I think it was the 2E did not have passenger oxygen fitted.
Actually, it was the other way around. The Trident One, and the Trident Three did not have passenger oxygen (in Britain, I am not sure about export models), the Trident Two did.
Same thing with most versions of the BAC-111, no passenger oxygen.
Never gonna grow up, never gonna slow down .... Barefoot Blue Jean Night
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 13, posted (5 months 4 days 4 hours ago) and read 4584 times:
Quoting Gonzalo (Thread starter): I had the ( wrong? ) idea about all the commercial / civil aircraft had weight on wheels sensors, to prevent in flight deployment of the T/R
They all have systems to prevent inadvertent T/R deployment. Those aren't always weight-on-wheels sensors. The 737, for example, can deploy off the radio altimeter (and hence can deploy in a very thin range of "in-the-air").
737tdi From United States of America, joined Sep 2007, 466 posts, RR: 0 Reply 14, posted (5 months 4 days 3 hours ago) and read 4528 times:
Quoting tdscanuck (Reply 13): They all have systems to prevent inadvertent T/R deployment. Those aren't always weight-on-wheels sensors. The 737, for example, can deploy off the radio altimeter (and hence can deploy in a very thin range of "in-the-air").
Tom
Tom: I believe once the "sync-loc" mod. was installed the reversers can not and will not deploy until weight on wheels. You can pull the handle but nothing will happen until then.
As far as the DC-8 the inboard reversers can be deployed at any time. There is a mechanical lock off of the nose landing gear to prevent deployment of the outboard reversers. I have flown many test hops where this system was verified and it feels like you hit a wall when those CFM-56-2s are reversed in flight. Remember the DC-8 does not have speedbrakes so they use the reversers to slow.
PGNCS From United States of America, joined Apr 2007, 2516 posts, RR: 45 Reply 15, posted (5 months 4 days 2 hours ago) and read 4496 times:
Quoting tdscanuck (Reply 13): Quoting Gonzalo (Thread starter): I had the ( wrong? ) idea about all the commercial / civil aircraft had weight on wheels sensors, to prevent in flight deployment of the T/R
They all have systems to prevent inadvertent T/R deployment. Those aren't always weight-on-wheels sensors. The 737, for example, can deploy off the radio altimeter (and hence can deploy in a very thin range of "in-the-air").
Tom.
The DC-9 series has nothing to inhibit inflight deployment (WoW or RA, etc.) other than good sense. In over 10,000 hours on the aircraft I have never seen it be an issue. Of course the throttle does have to be at idle first, so I suppose you could make the argument that this interlock is a system to prevent inadvertent deployment, though it will NOT prevent inflight deployment regardless of altitude.
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 16, posted (5 months 4 days 2 hours ago) and read 4480 times:
Quoting 737tdi (Reply 14): Tom: I believe once the "sync-loc" mod. was installed the reversers can not and will not deploy until weight on wheels. You can pull the handle but nothing will happen until then.
The sync-lock is triggered by microswitches on the T/R deploy handles...the sync-locks will release as soon as you pull up on the handles. They're there to prevent a Lauda-type incident by providing an independent level of redundancy in the actuation hardware. The sync-locks will not prevent an intentional deployment.
Assuming that the pilot pulls the levers (releasing the sync locks), another relay needs to actuate to command hydaulic fluid to the actuators. The ground for that relay can go through two paths...one is the air/ground system (basically weight-on-wheels) and the other is the radio altitude from the flight control computer (less than 10'). Either path is sufficient to allow deployment so if you're on the ground (specifically, the air/ground relay is in ground) or the FCC thinks you're less than 10' from the ground, the T/R's will deploy.
If you have access, check out 737 AMM SDS 78-34-00 for more details.
The key to most T/R systems is preventing *inadvertent* deployment. Many aircraft will inhibit deployment in flight regardless what the crew says but all of them don't want the T/R's to ever deploy unless the flight crew wants them to.
There are also regs (someone else will have to find em) that say how many O2 masks are required per passenger. I was a flight attendant on a US regional and though we "briefed" the masks, we did not have more than 1 for each 10 passengers on board the aircraft.
atct
Real pilots fly planes that take and measure oil in gallons
IIRC (haven't really looked at that system page in a while) it's 10feet on the RA you can deploy the reversers on the 737. I don't know why anyone would want to do that but you could.
longhauler From Canada, joined Mar 2004, 4280 posts, RR: 36 Reply 22, posted (4 months 2 weeks 4 days ago) and read 2364 times:
Quoting tdscanuck (Reply 13): They all have systems to prevent inadvertent T/R deployment. Those aren't always weight-on-wheels sensors. The 737, for example, can deploy off the radio altimeter (and hence can deploy in a very thin range of "in-the-air").
That must have been later B737s, the B737s I flew (-200, and -200ADV) required positive oil pressure and weight on wheels to power the hydraulics to work.
In fact, some of them also had a squat switch in the nose wheel as well, which also had to be activated. Makes sense, the -200 had huge buckets and in a nose high attitude, you could scrape them on the ground.
Never gonna grow up, never gonna slow down .... Barefoot Blue Jean Night
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 23, posted (4 months 2 weeks 3 days 12 hours ago) and read 2228 times:
Quoting longhauler (Reply 22): That must have been later B737s, the B737s I flew (-200, and -200ADV) required positive oil pressure and weight on wheels to power the hydraulics to work.
Yes, I was talking -300 and onwards. -100/-200 had a totally different reverser system.
NZ lost a DC-8 at AKL on a training flight when a TR was activated on a touch-and-go. My father was an FE with NZ at the time and scheduled to be on that flight, but was swapped out for other duties.
fsnuffer From United States of America, joined Jun 2007, 229 posts, RR: 0 Reply 26, posted (4 months 2 weeks 2 days 13 hours ago) and read 2036 times:
While at Offutt there were rumors RC-135 pilots were deploying TR during the flare and it was called a "Shemya Short Landing". Since I never took a flight to Shemya, it is only second hand.
longhauler From Canada, joined Mar 2004, 4280 posts, RR: 36 Reply 27, posted (4 months 2 weeks 2 days 11 hours ago) and read 2025 times:
Quoting Kaiarahi (Reply 24): NZ lost a DC-8 at AKL on a training flight when a TR was activated on a touch-and-go. My father was an FE with NZ at the time and scheduled to be on that flight, but was swapped out for other duties.
When I hear stories like this, I often think of fate.
My father was supposed to be the Second Officer of the Trans-Canada DC-8 that was lost at YUL in 1963, but the crew's inbound flight was late and a reserve crew was used instead. When I asked him about that, he just said, "If I were on the aircraft, it wouldn't have crashed, I guess it was meant to crash!"
Maybe it was the same in your Father's case. His hand on the thrust levers might have had a different weight, angle, etc ... and the T/R would not have been activated.
Never gonna grow up, never gonna slow down .... Barefoot Blue Jean Night
Kaiarahi From Canada, joined Jul 2009, 2579 posts, RR: 24 Reply 28, posted (4 months 2 weeks 9 hours ago) and read 1664 times:
Fate for sure! I can't find the accident report archived anywhere, but the story within NZ at the time was that the training captain (left seat) may have hooked his finger around the "leg" of #4 throttle (rather than the knob) and pulled it back aggressively (they were doing engine out drills), causing the TR to jerk up and deploy. If he'd had his hand on the top of the throttle, it likely wouldn't have happened. As I recall the report, there was a recommendation for better TR lever mechanical protection, but I don't remember if it was implemented. I do remember that when I was learning to fly Hercs a few years later, simulated engine out training was done with a smooth throttle retardation - the AKL accident was still fresh in everyone's mind.
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