Air India Flight AI171 (Boeing 787-8) Crash

[FowVay]

The 787 is unique in several ways and is much different from a traditional jetliner. The big difference with regard to the powerplants (disregard that it's a composite airplane) is that everything is electric. It doesn't use bleed air for air conditioning or use engine/auxiliary drive for fuel pumps. Everything is electric. The fuel systems had 2 A/C pumps per tank and a extra D/C pump in the center tank for emergencies in case the A/C pumps fail. That means they're battery driven while the A/C pumps are generator driven. This is a hugely reliable way of doing this.

As for fuel temps.. all of these commercial planes have operating limits. I don't know about the 787 since I don't have a manual in front of me but generally, a fuel temperature of 55ºC (over 130ºF) is the operating limit. This is where vapor lock or line vaporization becomes critical. I have no idea what the ramp temperatures were that day but I am certain the flight crew knew if there was any concern. And once the engines are running, there's not going to be any vapor lock in the system. Jet engines don't 'inject' fuel into the combustor... they pour it in like a garden hose. The idle and taxi time should have taken care of that. And it had a 2 mile runway to blast down before takeoff.

If the cause turns out to be fuel starvation then there was something else going on that would have brought the plane down otherwise. I remember when the 787 was first introduced there were numerous fires in the fwd electronics compartment. This was all tied to the Li-Ion batteries that they were using. Only a proper investigation is going to answer all of these questions that we all have. I just wish the investigators would hurry up and throw us a bone.

 

[Just a civilian pilot]

The 787 is unique in several ways and is much different from a traditional jetliner. The big difference with regard to the powerplants (disregard that it's a composite airplane) is that everything is electric. It doesn't use bleed air for air conditioning or use engine/auxiliary drive for fuel pumps. Everything is electric. The fuel systems had 2 A/C pumps per tank and a extra D/C pump in the center tank for emergencies in case the A/C pumps fail. That means they're battery driven while the A/C pumps are generator driven. This is a hugely reliable way of doing this.

As for fuel temps.. all of these commercial planes have operating limits. I don't know about the 787 since I don't have a manual in front of me but generally, a fuel temperature of 55ºC (over 130ºF) is the operating limit. This is where vapor lock or line vaporization becomes critical. I have no idea what the ramp temperatures were that day but I am certain the flight crew knew if there was any concern. And once the engines are running, there's not going to be any vapor lock in the system. Jet engines don't 'inject' fuel into the combustor... they pour it in like a garden hose. The idle and taxi time should have taken care of that. And it had a 2 mile runway to blast down before takeoff.

If the cause turns out to be fuel starvation then there was something else going on that would have brought the plane down otherwise. I remember when the 787 was first introduced there were numerous fires in the fwd electronics compartment. This was all tied to the Li-Ion batteries that they were using. Only a proper investigation is going to answer all of these questions that we all have. I just wish the investigators would hurry up and throw us a bone.

Airbus limitations section:

If you were unlucky enough to reach these temperatures, a caution will advise you.

Edit: I have had high fuel temperatures problems on the ground in Las Vegas because we were taxiing for over 1 hour on the ground ( we got a caution light ).

Triggering Conditions:
This alert triggers when the fuel temperature:
‐ In outer cell, is above 55 °C on ground
‐ In outer cell, is above 60 °C in flight
‐ In inner cell, is above 45 °C on ground
‐ In inner cell, is above 54 °C in flight.

 On the ground:
 If the fuel temperature reaches 55° C in outer tank or 45° C in inner tank:
LIMITED TAXI TIME
Note: Monitor fuel temperature. Takeoff may be performed until the fuel temperature
reaches 60°C in the outer tank or 54°C in the inner tank.
 If the fuel temperature reaches 60° C in outer tank or 54° C in inner tank:
DELAY T.O.
ENG MASTER (AFFECTED SIDE).............................................................................OFF

JET A1/JP8/
N°3 JET
JET A JP5 RT TS-1 JET B JP4
MINI -43 °C -36 °C (1) -42 °C -45 °C -45 °C -46 °C -54 °C
MAXI 54 °C 49 °C
(1) For JET A only, if TAT reaches -34 °C, monitor the fuel temperature on the FUEL SD page.

 

[FowVay]

I reviewed the current weather at the Ahmedabad airport and it's cooler and dryer there than it is in Atlanta. I think it would be a long shot to blame vapor lock. But... it's just one more speculative guess at this moment.

 

[Just a civilian pilot]

I reviewed the current weather at the Ahmedabad airport and it's cooler and dryer there than it is in Atlanta. I think it would be a long shot to blame vapor lock. But... it's just one more speculative guess at this moment.

I am not saying some type of fuel problem didn’t cause the engines to quit but some guy on ( and he said he was a “ jet pilot “ ) YT speculating it all started with losing hydraulics and snowballed into fuel Vapor lock sounds crazy to me and I find it disturbing any “ jet pilot” would even post it.

 

[FowVay]

Yes, we're seeing quite a few experts speaking their minds on the internet. I saw one picture of a completely intact wing that had absolutely zero flap extension and I surprised nobody has run with it. The vapor lock was mentioned here a few posts/days ago so I just added my thoughts to that. No flaps, wrong lever actuated, gear stuck down, the RAT being out and spinning.... all great points of discussion.

These incidents are so horrible that they're hard for an empathetic person to discuss but the way the investigators pick it apart piece by piece is one of the most fascinating things I've witnessed.

 

[JimPghPA]

So far it looks like duel engine failure. But why is just speculative guessing.

There's still a lot to learn about this accident. Maybe we'll have to wait until the information from the boxes gets totally looked at.

 

[GON]

So far it looks like duel engine failure. But why is just speculative guessing.

There's still a lot to learn about this accident. Maybe we'll have to wait until the information from the boxes gets totally looked at.

It would be interesting to get a list of the actions performed on the heavy maintenance of the aircraft just weeks before the accident.

 

[4WD]

Ok, I give, what carrier flies out of IAH that has RR engines on the 787? UA uses GE.

British?

Yes, now waiting to board a B787-10 (UA) - TN lookup says Trent 1000 and just 2.6 years in service … Polaris 1A awaits !

 

[ms21043]

The 787 is unique in several ways and is much different from a traditional jetliner. The big difference with regard to the powerplants (disregard that it's a composite airplane) is that everything is electric. It doesn't use bleed air for air conditioning or use engine/auxiliary drive for fuel pumps. Everything is electric. The fuel systems had 2 A/C pumps per tank and a extra D/C pump in the center tank for emergencies in case the A/C pumps fail. That means they're battery driven while the A/C pumps are generator driven. This is a hugely reliable way of doing this.

As for fuel temps.. all of these commercial planes have operating limits. I don't know about the 787 since I don't have a manual in front of me but generally, a fuel temperature of 55ºC (over 130ºF) is the operating limit. This is where vapor lock or line vaporization becomes critical. I have no idea what the ramp temperatures were that day but I am certain the flight crew knew if there was any concern. And once the engines are running, there's not going to be any vapor lock in the system. Jet engines don't 'inject' fuel into the combustor... they pour it in like a garden hose. The idle and taxi time should have taken care of that. And it had a 2 mile runway to blast down before takeoff.

If the cause turns out to be fuel starvation then there was something else going on that would have brought the plane down otherwise. I remember when the 787 was first introduced there were numerous fires in the fwd electronics compartment. This was all tied to the Li-Ion batteries that they were using. Only a proper investigation is going to answer all of these questions that we all have. I just wish the investigators would hurry up and throw us a bone.

In regards to the 787 fuel system when compared to other aircraft.
It has 4 boost pumps, 2 in each wing, 2 override jettison pumps in the center tank and 1 DC pump in the left wing. The boost pumps are variable frequency AC, the O/J pumps are constant voltage/ frequency AC. The O/J pumps run at a higher pressure than the boost pumps, this ensures that the center tank fuel is used first. The DC pump in the left wing does nothing but feed the APU when it is started on battery power, that's all it does. If for some reason the boost and O/J pumps are not on, the engine fuel pumps will suction feed.
The engines have mechanical fuel pumps driven off the engine accessory gearboxes. Fuel from these pumps goes to the engines fuel metering units.

 

[Astro14]

Yes, now waiting to board a B787-10 (UA) - TN lookup says Trent 1000 and just 2.6 years in service … Polaris 1A awaits !

The professional's preference!

 

[Astro14]

It wasn’t caused by the flaps but this topic came up at work the other day.

A320 alpha lock protection:

This function inhibits slat retraction at high angles-of-attack and low speeds.
The SFCCs use corrected angle-of-attack (alpha) or airspeed information from the ADIRUs to
inhibit slat retraction.
When the FLAPS lever is set to 0, the slats alpha/speed lock function activates and inhibits slats
retraction, if:
‐ The AOA is above 8.0 °, or
‐ The speed is less than 165 kt.

The 787 has the same feature (inhibition) and will also extend leading edge devices in the event of high AOA.

The 757 has the same leading edge extension as a response to high AOA.

 

[y_p_w]

The professional's preference!

Rolls-Royce over GE?

 

[Astro14]

Rolls-Royce over GE?

I meant Polaris 1A. It’s close to the door, it’s close to the lavatory, it’s a bulkhead, and your body and head are away from the aisle. On the 767-300, it is also the pilot rest seat, so it is a bit of an insider perspective.

Nothing against GE, or Pratt. I’ve got a lot of time with General Electric engines in the F-14. I’ve got fair amount of time with General Electric engines on the 767–400.

I’ve got a lot of time with Pratt & Whitney in the F-14, and the 4060 on the 747-400, 2037s on the 757–200, and now, 4060 on the 767-300.

I’ve got a lot of time with the RB-211 on the 757-200.

In general, if you treat the engine, well, it’ll treat you well. Goes for everything I’ve ever flown.

I had a lot of TF-30s stall on me, but that’s because the engine was never designed for the application (fighter) and we were hard on them out of necessity. I have told a few stories about that in my F-14 thread, and in general, if you were quick in responding to the engine, to the stall, you could save the motor. I had a few shutdowns in Flight, Fire, fuel leak, etc. but I never had one come apart.

If you were slow to respond, and by that I mean more than a second or two, you would destroy the engine.

 

[Brons2]

Yes, now waiting to board a B787-10 (UA) - TN lookup says Trent 1000 and just 2.6 years in service … Polaris 1A awaits !

UA's fleet page says their 787-10 run GE engines.

[edit] airfleet's page does seem to indicate that some of their recently delivered 787-10 have RR engines. For example:

https://www.airfleets.net/ficheapp/plane-b787-66990.htm

https://www.airfleets.net/ficheapp/plane-b787-66989.htm

https://www.airfleets.net/ficheapp/plane-b787-66988.htm

whereas MSN 66987 and 66986 have GE:

https://www.airfleets.net/ficheapp/plane-b787-66987.htm

But 66985 is RR again (?)

https://www.airfleets.net/ficheapp/plane-b787-66985.htm

I...don't get it. Did they order a tranche of RRs?

 

[Jimmy_Russells]

So far it looks like duel engine failure. But why is just speculative guessing.

There's still a lot to learn about this accident. Maybe we'll have to wait until the information from the boxes gets totally looked at.

'tis but a scratch!

 

[Astro14]

'tis but a scratch!

One of our training lectures had “duel displays” to describe two of something…. I kept critiquing it.

I see “duel” and think, “You have insulted my honor, good sir! It shall be pistols at dawn!”

You want me to think there are two of something, use “dual”.

 

[SC Maintenance]

One of our training lectures had “duel displays” to describe two of something…. I kept critiquing it.

I see “duel” and think, “You have insulted my honor, good sir! It shall be pistols at dawn!”

You want me to think there are two of something, use “dual”.

In the old south a Dual set of Duelling pistols was to be used, like this set used by Hamilton and Burr - now in a museum.

https://th-thumbnailer.cdn-si-edu.c...1bb6b9ac-71d7-4253-bdef-3850ea2b9d4f/ham7.jpg

 

[FowVay]

UA's fleet page says their 787-10 run GE engines.

[edit] airfleet's page does seem to indicate that some of their recently delivered 787-10 have RR engines. For example:

https://www.airfleets.net/ficheapp/plane-b787-66990.htm

https://www.airfleets.net/ficheapp/plane-b787-66989.htm

https://www.airfleets.net/ficheapp/plane-b787-66988.htm

whereas MSN 66987 and 66986 have GE:

https://www.airfleets.net/ficheapp/plane-b787-66987.htm

But 66985 is RR again (?)

https://www.airfleets.net/ficheapp/plane-b787-66985.htm

I...don't get it. Did they order a tranche of RRs?

If the photographs of those ship numbers match then all of those aircraft have GE engines. The fan cowlings are one major distinction between the Rolls and the General. If the engines are static and you're looking at the fans then note the the Rolls engines spin backwards from what the General's engines spin so the blades are distinctly different shape. Rolls-Royce uses expanded core titanium while GE uses carbon fiber for their blades.

Rolls-Royce Trent 1000

General Electric GEnx

 

[y_p_w]

UA's fleet page says their 787-10 run GE engines.

[edit] airfleet's page does seem to indicate that some of their recently delivered 787-10 have RR engines. For example:

https://www.airfleets.net/ficheapp/plane-b787-66990.htm

https://www.airfleets.net/ficheapp/plane-b787-66989.htm

https://www.airfleets.net/ficheapp/plane-b787-66988.htm

whereas MSN 66987 and 66986 have GE:

https://www.airfleets.net/ficheapp/plane-b787-66987.htm

But 66985 is RR again (?)

https://www.airfleets.net/ficheapp/plane-b787-66985.htm

I...don't get it. Did they order a tranche of RRs?

I don't think that site is correct. United doesn't list any RR engines for its 787 fleet.

https://www.united.com/en/us/fly/company/aircraft/uniteds-fleet.html​

Boeing 787​

Cruise speed: 560 mph​

Capacity: 219-318 passengers​

Propulsion: Two General Electric GEnx engines​

I look at the first one:

https://www.airfleets.net/ficheapp/plane-b787-66990.htm​

BOEING 787 - MSN 66990 N12021​

Planespotters says 2 GE engines.

https://www.planespotters.net/airframe/boeing-787-10-n12021-united-airlines/e9q49g​

N12021​

Boeing 787-10 Dreamliner​

United Airlines ​

Dec 2022​

C44W21Y253​

2x GE​

 

[Jimmy_Russells]

If the photographs of those ship numbers match then all of those aircraft have GE engines. The fan cowlings are one major distinction between the Rolls and the General. If the engines are static and you're looking at the fans then note the the Rolls engines spin backwards from what the General's engines spin so the blades are distinctly different shape. Rolls-Royce uses expanded core titanium while GE uses carbon fiber for their blades.

Rolls-Royce Trent 1000
View attachment 285306

General Electric GEnx
View attachment 285307

So not only do they drive on the wrong side of the road, but their engines also spin the wrong way.