Thrust Reverse use DHC Dash 8 series
While this accident was not to a DH8 but to a Fokker 50, it shows quite well what happens when the prop pitch is moved below the flight beta range.
Luxair Flight 9642 - Wikipedia, the free encyclopedia
The official report is to be found under http://www.gouvernement.lu/salle_pre...apport_eng.pdf , should You be interested.
So in a nutshell - this situation is best avoided.
Luxair Flight 9642 - Wikipedia, the free encyclopedia
The official report is to be found under http://www.gouvernement.lu/salle_pre...apport_eng.pdf , should You be interested.
So in a nutshell - this situation is best avoided.
On dash 100/200/300 you can select rev in flight, theres nothing to stop you, other than the threat of death!
Typically systems that could result in a loss of control if activated in the air are disabled even if selected.
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The dash is an old school design, which assumes that the pilot might one day need to do something in an emergency that no one could imagine at the design stage.
Indeed, putting the power levers into the ground beta range and below in flight would cause a fair amount of paper work. But so would hitting the back stop of the elevator in a Vne dive....and there's nothing stopping you doing that either! The dash is no airbus!
Not a dash, but clear to all rev is possible before main wheel touchdown.
Photos: Ilyushin Il-62M Aircraft Pictures | Airliners.net
Interestly, our ops manual for the dash did not allow to move the power levers below the flight detent before NOSE wheel (ie all wheels on the ground) due to control "issues"
There was a Fokker 50 on the IOM which tried it a while ago, selected rev just before touch down, the loss of airflow over the tail caused it to leave the Tarmac, there's an AAIB report about it somewhere. But another example that it is possible to do what ever you want with the older ac.
Indeed, putting the power levers into the ground beta range and below in flight would cause a fair amount of paper work. But so would hitting the back stop of the elevator in a Vne dive....and there's nothing stopping you doing that either! The dash is no airbus!
Not a dash, but clear to all rev is possible before main wheel touchdown.
Photos: Ilyushin Il-62M Aircraft Pictures | Airliners.net
Interestly, our ops manual for the dash did not allow to move the power levers below the flight detent before NOSE wheel (ie all wheels on the ground) due to control "issues"
There was a Fokker 50 on the IOM which tried it a while ago, selected rev just before touch down, the loss of airflow over the tail caused it to leave the Tarmac, there's an AAIB report about it somewhere. But another example that it is possible to do what ever you want with the older ac.
Last edited by adverse-bump; 19th Oct 2011 at 21:34.
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Well you may be able to select it but will it deploy if no weight on wheels?
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You can select full reverse in flight in the 100/300 series Dash 8s. The only thing that might inhibit you (other than fear of death) is a very loud beta warning horn and the power lever triggers that have to be "squeezed" to get past the stop.
Once the reverse selection is cancelled, you can expect a full blown prop overspeed. Not nice.
Once the reverse selection is cancelled, you can expect a full blown prop overspeed. Not nice.
i cannot say much about the dhc8 but in our cheyenne III its definitivly prohibited. when you see the amount of speed loss pulling flight idle with props forward you can imagine what happens when you go into ground idle /flat pitch or even reverse being airborne.
on the pt6a ground idle is not governor controlled so a prop "runaway" might occour doing it airborne. the enormous drag could result in a loss of control with catastrophic results.
but thats just a guess- i never tried it and i never saw it , i think you will find little pilots which can tell you from real experience what would happen. i heard some stories where guys after deploying parachute jumpers dived back to the field in ground idle on a caravan , but cannot confirm if its true.
on the pt6a ground idle is not governor controlled so a prop "runaway" might occour doing it airborne. the enormous drag could result in a loss of control with catastrophic results.
but thats just a guess- i never tried it and i never saw it , i think you will find little pilots which can tell you from real experience what would happen. i heard some stories where guys after deploying parachute jumpers dived back to the field in ground idle on a caravan , but cannot confirm if its true.
There is a beta backup mod for the dash 8 that prevents the props from going to ground beta in flight, you can select it, but it won't do it. This is in addition to the beta warning horn which sounds when you lift the triggers in flight.
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This is an excerpt from a memo from Bombardier regarding the above thread...
When the power levers are moved aft of the flt idle gate in flight, the propeller govenor, propeller overspeed govenor and the beta backup logic protection are all inhibited and propeller speed control is no longer available. In this condition the propeller(s) would be driven uncontrollably towards reverse pitch resulting in an overspeeding propeller and substantial engine damage leading to possible engine failure.....
Im no genius but that all sounds bad! Im not game to try it!
When the power levers are moved aft of the flt idle gate in flight, the propeller govenor, propeller overspeed govenor and the beta backup logic protection are all inhibited and propeller speed control is no longer available. In this condition the propeller(s) would be driven uncontrollably towards reverse pitch resulting in an overspeeding propeller and substantial engine damage leading to possible engine failure.....
Im no genius but that all sounds bad! Im not game to try it!
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Reverse Pitch airborne.
Not a Dash 8, but a C130 (KC130F model) Hercules carried out a total of 50 landings and take-offs from the USS Forrestal in 1963 (29 touch and go's - 21 unassisted stop and go). During the trials Reverse Thrust was selected whilst still several feet above the carrier deck so as to minimize the time to go from flight idle to max reverse. The aircraft was modified only in having the refuelling pods removed, a restrictor in the NLG strut and an improved fully modulated anti-skid system. Don't know about the J model C130, but the A-E & H models had only the "Step" over which the throttles had to be lifted to prevent going into reverse. For those interested the links below will take you to a summary of the trials onto and off the USS Forrestal and a 5 minute video with commentary.
C-130 Hercules Lands on U.S.S. Forrestal
C-130 Hercules Lands on U.S.S. Forrestal
righthandseat, I used the wrong term. The beta backup is standard and is not operational with the power levers below flight idle but the beta lockout is a mod that prevents the props going to ground beta irrespective of power lever position.
Many, many years years ago United did flight testing with Convair to see what would happen if a prop reversed in flight on a CV-440. They had one engine at METO and the other one pulled as far back through the gate as they could. I still remember the summary of the report - the plane was controllable but "the rate of descent never stabilized."
