Posts about: "RAT (Deployment)" [Posts: 361 Pages: 19]

Well, the certainly sound like they are working; failed engines sound different. No sign of smoke or damage either.

Conceivably, it could be a double engine failure but that's very unlikely.

Suggests dual engine shutdown/rollback (VFGs offline) with auto RAT deployment.
Full length departure.
Aircraft flaps/slats extended.
Mayday broadcast.
This has a long way to go. I wouldn't be judging the Liveware until the data\x92s been analyzed in detail.

You have heard AC with the RAT deployed HUNDREDS of times? The RAT is a last resort, when all other power sources have failed. All engines, the APU and (possibly) batteries on AC as the 787. Yet you have heard hundreds of RAT deployments passing overhead? Yeah, sure.

The video from the NE end of the runway, beside the RVR sensor shows a liftoff occurs abeam the closed high speed taxiway between C and D. Thats at 1250m to run to the DER. The first 10 seconds of flight is steady, and then the aircraft stops climbing and starts a gentle descent, and 5 seconds later the pitch starts to increase in 2 stages with impact around 20 seconds after liftoff. This is not the ADSB data, it is the video at the boundary on F/B.

The video take from the south end of the airport appears to show the RAT deployed.

The flight VAAH-EGLL is not a particularly heavy departure, the takeoff distance is not unreasonable for a twin jet, at under 7,000' from brakes release. I have limited developmental time only on the 787 before EIS, and I cannot recall any surprising latent threat in the performance of the aircraft for a premature flap retraction, and that certainly would not result in a RAT deployment. An accidental ATR low level off capture might get exciting for a few seconds, but it would not result in a RAT either.

The seat 11A pax survivor is remarkable.

Primary trigger: Loss of all four AC power sources.

• These include:
  • Left Integrated Drive Generator (IDG)
    
  • Right IDG
    
  • Left Backup Generator
    
  • Right Backup Generator
    Engine failure alone does not trigger the RAT, must be all of above

What does a RAT deployment sound like inside the cabin? Could the mere deployment be perceived as the 'loud bang' in a high stress situation?

IME, admittedly going back a few years, a RAT being propelled into its deployed position does indeed make a humungous bang.

In flight, the RAT deploys automatically if any of the following occur:
• both engines have failed
• all three hydraulic system pressures are low
• loss of all electrical power to captain’s and first officer’s flight
instruments
• loss of all four EMPs and faults in the flight control system occur on
approach
• loss of all four EMPs and an engine fails on takeoff or landing

(EMP = electric motor pump, hydraulic)
FYI the RAT is an emergency source for electrical and/or hydraulic power.

Regarding that possibility some members here are posting a scenario where RAT are deployed, could this be possible (im no 787 driver at all)?

1) Near the moment of Rotation or a few seconds after it, an Engine failure occurred. (Bird, Fod, Mx, Tech, etc)
2) By destiny irony as in Kegworth or Taipei aviators cut the good one by mistake.
3) No running engines, RAT comes alive...

May all RIP, such a sad day for us all...

and people are saying this happened all at the same time within 30-45 seconds ?

Yep, total rubbish - 45 years airline flying - deployed it only once and never saw it anywhere else.

Forgive me if appear to be being a bit pedantic but the 787 does not have IDGs and BUGs.
Each engine has two identical Variable Frequency Starter Motor Generators.
They are a combined starter motor and generator.

More in this ancient thread here-
787 electrical system - variable frequency generators?

Every 787 in service has had the RAT deployment tested during Boeing/Customer flights prior to delivery.

Many people living/working in the Everett or Charleston areas will have heard the RAT many times.

I am not a pilot so apologies if this is a basic question.

Under what conditions will the RAT deploy? Is this automated or does the PF / PM need to hit a switch? <-- [Edit] I see this was largely answered in post 369. Thanks!

Watching the CCTV from the airport, it doesn't look like there was much time to do anything. I'm surprised someone called a Mayday (if that's true). And even to me, it seems pretty clear that bird never had enough power to go much of anywhere except where it did.

All so very tragic.

I can confirm that this happens in the Blagnac area too!

There are people in the world who have a different, less limited lived experience from you.

As noted in my profile, I live in the Apple Maggot Quarantine area. Specifically, I live in Lynnwood, Washington directly under the approach path for Paine Field's runway 34 Left, and I've been there since 2007. I lived in Mukilteo from 2000-2007, which is more next to the runway than under it. I also own and operate a small aircraft based at Paine Field and am outside on the ramp at least every other day. Boeing manufactures the 777 and 787 at Paine field. Two thousand, nine hundred and fourty-six of them have been made since 2000, when I moved here. The RAT is deployed and tested during EVERY SINGLE first flight of every aircraft Boeing produces that has a RAT installed. And sometimes it requires a re-test on subsequent flights.

So yeah, I have heard a deployed RAT, from the ground, HUNDREDS of times. I've heard it while preflighting my airplane, I've heard it while mowing my lawn, I've heard while lying in bed. And this is exactly what they always sounds like. Another poster compared it to the sound of a T-6 Texan, which is really quite similar. You can find dozens and dozens of videos on YouTube of aircraft landing at Paine Field with the RAT out. It's not rare, it happens daily.

Would explain the lack of thrust, but not the RAT deployment.

Thanks for your input and a reminder to others manners cost nothing! You don't know who you're speaking to

There are no IDGs on a 787. There are 4 identical variable frequency starter-generators.

For those still under the impression that the takeoff or rotation was at the runway end... In the video of the CCTV camera you can see rotation happens basically behind the small structure in the foreground. Unless I am severely mistaken... Knowing the approximate rotation of the camera, one can simple draw a line until it intersects with both the structure and the runway:



Yes, it is just an approximation, but I'd say they still had a decent chunk of runway left, and not in any way close to taking out antennas on the opposite end.

So... likely not at MTOW, not using the full runway, normal rotation, followed by videos of it with RAT deployed which should only happen upon loss of all electrical/hydraulical sources, which should only really happen on loss of both engines without APU running, combined with barely (if any) sound produced by the engines in said videos... It leads me to form some sort of image of what happened. Could still be completely wrong.

I have done a RAT deployment test flight on a previous type, and even though I was prepared for it, it was still a bit of a shock to see the cockpit go mostly blank before reconfiguring itself. I don't know how quickly the 787 would reconfigure, if there is any downtime at all, but that would not have been a thing you'd expect at 100-200ft AGL. I do not know how many of us would quickly overcome the startle.