2025-06-12T09:23:00
permalink Post: 11898927
Subjects: None
2025-06-13T06:26:00
permalink Post: 11900060
Re fuel contamination. Shouldn’t the engines be feeding from separate tanks at that point? What are the odds of simultaneous Engine Failure? (Basing that on there is little yaw or wing drop to the live)
It’s years since I looked at it. I thought it was in the FARs explicitly but I can only find CFR 25.1309 states the safety analysis for equipment systems and installations that would be likely encompass this.
It’s years since I looked at it. I thought it was in the FARs explicitly but I can only find CFR 25.1309 states the safety analysis for equipment systems and installations that would be likely encompass this.
Subjects: Engine Failure (All) Fuel (All) Fuel Contamination
2025-06-14T04:00:00
permalink Post: 11901123
Ex petroleum lab technician and tank farm sampler here. We would occasionally get fuel samples from crashed aircraft to test for contamination. One test was for water and sediment/microorganism sludge.
In this accident, fuel contamination continues to be dismissed as a cause, because no other aircraft have reported issues. But there has been no discussion regarding the airport's fuel storage, transfer, or filtration systems. Water and sediment naturally settles at the bottom of fuel storage tanks. If this aircraft received fuel drawn from the bottom of a storage tank, in the absence of a proper filtration system, it\x92s possible that it was contaminated. The next aircraft may have received fuel from a different storage tank with good fuel.
In this accident, fuel contamination continues to be dismissed as a cause, because no other aircraft have reported issues. But there has been no discussion regarding the airport's fuel storage, transfer, or filtration systems. Water and sediment naturally settles at the bottom of fuel storage tanks. If this aircraft received fuel drawn from the bottom of a storage tank, in the absence of a proper filtration system, it\x92s possible that it was contaminated. The next aircraft may have received fuel from a different storage tank with good fuel.
Fuel contamination is certainly a valid theory. The main thing working against it is that it would seem from the aircraft's flight path is that both engines failed at exactly the same time and lost thrust simultaneously. The chances of this are non zero, but remote. I say that as there appears to be no yaw, or other controlling of the aircraft - either by pilot or automation - that would suggest an asymmetric thrust scenario, even for a few seconds.
Yes, Jetstar had the biocide issue but did not immediately hit both engines within seconds of each other.
It's my understanding that both engines draw fuel from independent sources during that time (which may be fed from a common source (eg central tank). But again, the odds of both failing at the exact same instant is low, but not zero.
Subjects: Biocide Engine Failure (All) Engine Shutdown Fuel (All) Fuel Contamination
2025-06-14T05:12:00
permalink Post: 11901139
""The chances of this are non zero, but remote. I say that as there appears to be no yaw, or other controlling of the aircraft - either by pilot or automation - that would suggest an asymmetric thrust scenario, even for a few seconds.""
Look again at the initial video. The heading of the a/c is definitely right of centerline. Look at the background as the fuselage points right, and the aircraft "drifts" left. Something's up, either an input yaw to counter a cross, or asymmetric thrust. Not a lot, but noticeable. It diminished as the a/c disappears.....So, not an exact simultaneous loss of thrust, but almost certainly a single cause. Can't see the Rudder, nor the orientation of the gear, either or both could cause the slight yaw I see.
Look again at the initial video. The heading of the a/c is definitely right of centerline. Look at the background as the fuselage points right, and the aircraft "drifts" left. Something's up, either an input yaw to counter a cross, or asymmetric thrust. Not a lot, but noticeable. It diminished as the a/c disappears.....So, not an exact simultaneous loss of thrust, but almost certainly a single cause. Can't see the Rudder, nor the orientation of the gear, either or both could cause the slight yaw I see.
I don't have the perf data, but I'd be surprised if a heavyish (but probably not at MTOW) 787 would climb like that for the next 5 seconds or so on one engine with the gear out.
edit - found the METARs on page 2. Wind 10 mins prior 250/7 which would give 2-3 kts R wind. Not a lot admittedly, but it was consistently from the direction into which an aircraft would yaw to maintain RWY TRK.
Last edited by compressor stall; 14th Jun 2025 at 05:25 .
Subjects: None
1 user liked this post.
2025-06-17T11:26:00
permalink Post: 11904221
If it's fuel supply issues...
I understand that the 787 is able to feed both engines from a common centre tank on takeoff. Most other aircraft feed each engine independently from each side until a safe(r) stage of flight.
\xa7 25.953 Fuel system independence. Each fuel system must meet the requirements of \xa7 25.903(b) by\x97
(a) Allowing the supply of fuel to each engine through a system independent of each part of the system supplying fuel to any other engine; or
(b) Any other acceptable method.
\xa7 25.903 Engines.....
(b) Engine isolation. The powerplants must be arranged and isolated from each other to allow operation, in at least one configuration, so that the failure or malfunction of any engine, or of any system that can affect the engine, will not\x97
(1) Prevent the continued safe operation of the remaining engines; or
(2) Require immediate action by any crewmember for continued safe operation.
I'd be interested in any history or understanding as to why Boeing went with the common tank approach on takeoff?
\xa7 25.953 Fuel system independence. Each fuel system must meet the requirements of \xa7 25.903(b) by\x97
(a) Allowing the supply of fuel to each engine through a system independent of each part of the system supplying fuel to any other engine; or
(b) Any other acceptable method.
\xa7 25.903 Engines.....
(b) Engine isolation. The powerplants must be arranged and isolated from each other to allow operation, in at least one configuration, so that the failure or malfunction of any engine, or of any system that can affect the engine, will not\x97
(1) Prevent the continued safe operation of the remaining engines; or
(2) Require immediate action by any crewmember for continued safe operation.
I'd be interested in any history or understanding as to why Boeing went with the common tank approach on takeoff?
Last edited by compressor stall; 17th Jun 2025 at 11:42 .
Subjects: Centre Tank
2025-06-17T11:47:00
permalink Post: 11904234
Actually the engines are fed by all tanks during take off. (L engine: L wing tank + Center tank (if filled) / R engine: R wing tank + Center tank (if filled)).
Due to the fuel pressures of the feed pumps (that are all running) the center tank fuel is used first. In case the pump in the center tank fails or the center tank is empty the fuel from the wing will be used w/o any switch over taking place as the wing feed pumps are already running.
Due to the fuel pressures of the feed pumps (that are all running) the center tank fuel is used first. In case the pump in the center tank fails or the center tank is empty the fuel from the wing will be used w/o any switch over taking place as the wing feed pumps are already running.
Subjects: Centre Tank EDML Fuel (All) Fuel Pumps
2025-06-22T07:07:00
permalink Post: 11908309
1. That happens from time to time and its the way things are done in India and it's only newsworthy now by association (not causation), or
2. The DGCA need to be seen to be doing something, and that's some low hanging fruit in an otherwise vacuum of information.
Subjects: DGCA
1 user liked this post.