June 15, 2025, 12:00:00 GMT
permalink Post: 11902407
What if the PF called stop just before V1and closed the thrust levers but either changed his mind or was overridden by the other pilot, who rapidly pushed the thrust levers back up. Could this trigger a TCMA intervention and subsequent dual engine shutdown as it was still on the runway at this point? Hopefully not.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Dual Engine Failure Engine Failure (All) Engine Shutdown
June 15, 2025, 21:56:00 GMT
permalink Post: 11902882
Do not discount the mistaken early flap retraction scenario too easily. Mull on this:
PF commanded gear up on attaining positive rate of climb, fixating on the HUD.
PM mistakenly raise flap lever from 5 to Flap 1 gate. Thrust reduced to Climb Thrust. Landing gear remained deployed. Massive loss of lift misidentified as loss of thrust. If any one pilot just had a dual engine failure scenario on a recent sim ride, brain and muscle memory would jump to loss of thrust in dual engine, prompting them to accomplish the recall memory items which called for both engine fuel control switches to CUTOFF and then RUN, and physically deployed the RAT.
There would be immediate loss of thrust with the engine taking time to recover , if at all, at such low airspeed!
The rest is left for Ppruners\x92 imagination.😖🥴😬
PF commanded gear up on attaining positive rate of climb, fixating on the HUD.
PM mistakenly raise flap lever from 5 to Flap 1 gate. Thrust reduced to Climb Thrust. Landing gear remained deployed. Massive loss of lift misidentified as loss of thrust. If any one pilot just had a dual engine failure scenario on a recent sim ride, brain and muscle memory would jump to loss of thrust in dual engine, prompting them to accomplish the recall memory items which called for both engine fuel control switches to CUTOFF and then RUN, and physically deployed the RAT.
There would be immediate loss of thrust with the engine taking time to recover , if at all, at such low airspeed!
The rest is left for Ppruners\x92 imagination.😖🥴😬
A loss of lift AND thrust at this critical juncture could have had caused this awful disaster. I think the data recorders have already revealed the cause but If it's this, then I don't think we will hear much anytime soon.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Dual Engine Failure Engine Failure (All) Fuel (All) Fuel Cutoff Switches Memory Items Muscle Memory RAT (All) RAT (Deployment) RUN/CUTOFF
June 19, 2025, 20:20:00 GMT
permalink Post: 11906336
I have read that TCMA can not activate unless TL set to idle . How about this made up scenario . During takeoff run close to takeoff speed PF decides to reject for ANY reason and moves TL-s to idle . PM (captain ? ). Says my airplane we are continuing and move TL-s back to full trust . TCMA triggers and shuts off the fuel . I am not implying that crew did anything wrong .
Subjects: None
June 19, 2025, 20:52:00 GMT
permalink Post: 11906364
The type of switch being discussed is the specific type reported as being liable to problems. The SAIB is here
https://ad.easa.europa.eu/blob/NM-18...SIB_NM-18-33_1
and specifies a part number for the B788 as 4TL837-3D
That's a TL series switch with 4 poles (the "4" in "4TL"), a "type D" lock (meaning locked out of centre position per the Honeywell data sheet - the "D" in "3D." This is a photo of one:
You can find the manufacturer's datasheet here: https://octopart.com/datasheet/4tl83...ywell-25749542
Problems with critical switches aren't new on 787-8s. For instance, in addition to the SAIB above, there's this AD: https://www.federalregister.gov/docu...pany-airplanes
Looking at the photo above, it isn't just wear that's potentially an issue, but foreign object impingement. There don't appear to be gaitors fitted to these switches in the 788, so the locking mechanisms are potentially susceptible to a build-up of material if not kept clean. There are a range of other failure modes possible, whilst the SAIB specifically describes found-in-the-field problems with these switches.
Yes, they're chunky, and very positive when new. That doesn't mean they shouldn't be discussed.
That's a TL series switch with 4 poles (the "4" in "4TL"), a "type D" lock (meaning locked out of centre position per the Honeywell data sheet - the "D" in "3D." This is a photo of one:
You can find the manufacturer's datasheet here: https://octopart.com/datasheet/4tl83...ywell-25749542
Problems with critical switches aren't new on 787-8s. For instance, in addition to the SAIB above, there's this AD: https://www.federalregister.gov/docu...pany-airplanes
Looking at the photo above, it isn't just wear that's potentially an issue, but foreign object impingement. There don't appear to be gaitors fitted to these switches in the 788, so the locking mechanisms are potentially susceptible to a build-up of material if not kept clean. There are a range of other failure modes possible, whilst the SAIB specifically describes found-in-the-field problems with these switches.
Yes, they're chunky, and very positive when new. That doesn't mean they shouldn't be discussed.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Air Worthiness Directives Honeywell Special Airworthiness Information Bulletin
July 14, 2025, 19:49:00 GMT
permalink Post: 11922458
I always started from the left on shutdown, so 1 then 2 (and in my golden age 3 then 4) Do FOs start from the right? If I ever noticed, I don't remember now.
Subjects: None