AAL 1632 Overrun at KDFW, 2/10/2024
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AAL 1632 Overrun at KDFW, 2/10/2024
Given the recent UAL maintenance scrutiny, this incident involving a AAL 737NG “brake system anomaly” is worth noting. Post incident, hydraulic and electrical problems were discovered on the brake system, likely the result of a maintenance action on 2/6/2024.
Aircraft ended up in the overrun area of 17L at DFW. Might have been more interesting if this had occurred (landing or RTO) at the flight’s departure airport, DCA (7100 ft), instead of DFW (8500 ft).
NTSB Aviation Investigation Preliminary Report - AAL 1632, N991AN
Aircraft ended up in the overrun area of 17L at DFW. Might have been more interesting if this had occurred (landing or RTO) at the flight’s departure airport, DCA (7100 ft), instead of DFW (8500 ft).
NTSB Aviation Investigation Preliminary Report - AAL 1632, N991AN
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Data also showed the engine 1 and 2 thrust reverser parameters [Eng1
and Eng2 TR Dply-DEU] transitioned from “stowed” to “deployed” about 8 seconds after
touchdown. They remained deployed for about 12 seconds, were stowed for about 6 seconds,
and then re-deployed for the remainder of the landing rollout.
Does someone have an, ahem, "educated guess" on AAL's 737 thrust reverser use language? Specifically, when to stow.
and Eng2 TR Dply-DEU] transitioned from “stowed” to “deployed” about 8 seconds after
touchdown. They remained deployed for about 12 seconds, were stowed for about 6 seconds,
and then re-deployed for the remainder of the landing rollout.
Does someone have an, ahem, "educated guess" on AAL's 737 thrust reverser use language? Specifically, when to stow.
Most US airlines want reverse reduced to idle at 80 knots. Mostly for FOD prevention. Many pilots choose to come completely out of reverse at that point. I suspect based on reverse on this flight they came out at 80 knots, realized they were not getting proper wheel braking and reinstated reverse at that point.
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Most US airlines want reverse reduced to idle at 80 knots. Mostly for FOD prevention. Many pilots choose to come completely out of reverse at that point. I suspect based on reverse on this flight they came out at 80 knots, realized they were not getting proper wheel braking and reinstated reverse at that point.
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I seemed to remember new checks were introduced long time back which might have involved spinning up wheel transducers (the original Maxaret worked on the wheel it was fitted to, so no cross over issue).
Similar incident "Runway overrun following brake failure, Boeing 737-247, January 19, 1995 at ATL" same airline and more basic model.
Also On Oct. 17, 2019, PenAir flight 3296, a Saab SA-2000, Alaska.
Found this instruction post A320 minor miss-hap when more than one transducer is changed.
NOTE : If the MLG WHEEL TACHOMETER DRIVING TOOL is not available, as an alternative you can use:
- two standard drilling machines with the DRIVING ADAPTOR (98D32403004000).
Similar incident "Runway overrun following brake failure, Boeing 737-247, January 19, 1995 at ATL" same airline and more basic model.
Also On Oct. 17, 2019, PenAir flight 3296, a Saab SA-2000, Alaska.
Found this instruction post A320 minor miss-hap when more than one transducer is changed.
NOTE : If the MLG WHEEL TACHOMETER DRIVING TOOL is not available, as an alternative you can use:
- two standard drilling machines with the DRIVING ADAPTOR (98D32403004000).
Last edited by aeromech3; 25th Mar 2024 at 18:32.
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At 60 KIAS move reverser levers to forward idle thrust position and stow by 40 KIAS.
My airline (US large Cargo Airline) has changed our thrust reverser normal procedure to just going to reverse idle until 60 knots under “Normal” conditions. We can use full reverse thrust at our discretion whenever we feel the need, but on a normal landing, just reverse idle is sufficient. From what we were told, this procedure is becoming an industry standard as it reduces engine wear. Perhaps this could explain the strange reverser deployment in this incident.
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My airline (US large Cargo Airline) has changed our thrust reverser normal procedure to just going to reverse idle until 60 knots under “Normal” conditions. We can use full reverse thrust at our discretion whenever we feel the need, but on a normal landing, just reverse idle is sufficient. From what we were told, this procedure is becoming an industry standard as it reduces engine wear. Perhaps this could explain the strange reverser deployment in this incident.
The important thing is to get the reversers out as soon as practical after touchdown - even at reverse idle the ram drag at landing speeds is huge.
Because of that velocity squared thing, the ram drag (and hence the reverser effectiveness) drops rapidly as you slow - plus if you have any reverse thrust asymmetry, directional control can become difficult as you slow and you lose rudder effectiveness.
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I no longer have access to the various FCOMs, but I believe that is common to all Boeing models.
The important thing is to get the reversers out as soon as practical after touchdown - even at reverse idle the ram drag at landing speeds is huge.
Because of that velocity squared thing, the ram drag (and hence the reverser effectiveness) drops rapidly as you slow - plus if you have any reverse thrust asymmetry, directional control can become difficult as you slow and you lose rudder effectiveness.
The important thing is to get the reversers out as soon as practical after touchdown - even at reverse idle the ram drag at landing speeds is huge.
Because of that velocity squared thing, the ram drag (and hence the reverser effectiveness) drops rapidly as you slow - plus if you have any reverse thrust asymmetry, directional control can become difficult as you slow and you lose rudder effectiveness.
Interestingly, the deceleration on the DFDR plots is constant from the TR deploy until they’re stowed the first time. I would have thought it would be steeper at high speeds given the brakes weren’t working and the TRs were at Max.
Remember that velocity squared thing applies to kinetic energy as well - there is four times the kinetic energy at 120 knots that needs to be dissipated as there is at 60 knots...
In normal use since auto brakes maintain a deceleration rate there is often little or no wheel brake action at higher speeds. If full reverse is used that will meet the deceleration rate called for at lower auto brake settings. As the aircraft slows and reverse thrust becomes less effective or is phased out wheel braking increases to maintain the same deceleration. What is a bit odd in this incident is they appear to have wheel brakes functioning as they went off the end. I have long forgotten my 737 systems so perhaps they were able to manually select a alternative mode.
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Airbus (at least on the 320 series) says 70 knots to select idle.
