Dreamliner teething problems continue

Boeing and APU manufacturer Hamilton Sundstrand are being forced into an APU revision on all 787 Dreamliners. Currently, if the APU is shut down, and the inlet door is closed, heat from the APU operation continues to build inside the tail cone. After 20 minutes or so, the shaft of the APU bows, and can take up to two hours to straighten. If the APU is started between 20 and 120 minutes after shutting off, a failure message appears in the cockpit, and significant damage can occur to the APU, which then must be inspected with a borescope.

Boeing has a new shut down procedure that includes leaving the switch in the on position after shutting down, which requires the use of ground power, or the door will close after about 15 minutes, when the APU battery is drained.

There is no word on what is being done on a revision to allow more cooling to the APU, to prevent the shaft distortion.

As Boeing 787s re-enter service on routes around the world following the aircraft’s prolonged grounding for battery problems, the company is already busy resolving other issues that were emerging before they ceased flying in mid-January.

Most of these problems, such as a string of failures concerning power panels in the electrical system unrelated to the later lithium-ion battery problem, fell into the ‘teething trouble’ category which Boeing uses to describe the steep learning curve of early service life.

These issues impacted the early dispatch reliability of the aircraft, giving it a reliability level in the high 90% levels, roughly similar to the initial performance of the 777-200 shortly after its entry into service in mid-1995.

Although fixing many of these issues pale by comparison with the engineering resources involved with solving the battery problem, at least one concern with the operation of the auxiliary power unit (APU) has prompted Boeing and the unit’s manufacturer Hamilton Sundstrand into a design revision.

Operators have discovered that after the APS5000 APU is shutdown with the inlet door closed after landing, heat continues to build up in the tail compartment. After some 20 min. this causes the rotor shaft to bend or ‘bow’, and the shaft takes up to two hours to straighten back out.

Source

Is that as bad as it sounds for Epic Oops? I mean, how hard is it to have a generator on a vehicle, really? I know that's a major oversimplification of how it operates on an airplane, but not really for the role it plays, is it?

Boeing just hasn't been having the best of luck recently. I'd worry, but Airbus isn't exactly wearing the mantle of perfection themselves. I like driving better and better.

Originally posted by Zaphod58

There is no word on what is being done on a revision to allow more cooling to the APU, to prevent the shaft distortion.

If they retain me as a design engineer, I'll show them a way to keep the door open until the temperature falls below a safe level. I'll only charge them a few hundred thousand.

Alternatively, I'll show them how to incorporate a blower system to ventilate the APU housing until it cools to a safe level.

reply to post by Bedlam


It sounds like they need the help. I bet they'd jump at the chance to get help that cheaply, as opposed to what it usually costs.

reply to post by Wrabbit2000


It's a generator for when the engines aren't running basically. One of the reasons that this hurts is because ANA and JAL both operate domestically with the 787, which means quick turn times. They can't wait two hours for it to cool off.

Originally posted by Bedlam

Originally posted by Zaphod58

There is no word on what is being done on a revision to allow more cooling to the APU, to prevent the shaft distortion.

If they retain me as a design engineer, I'll show them a way to keep the door open until the temperature falls below a safe level. I'll only charge them a few hundred thousand.

Alternatively, I'll show them how to incorporate a blower system to ventilate the APU housing until it cools to a safe level.

This is a relatively minor problem (which I think was the point of your post). I don't doubt their ability to make it harder to find a solution than it needs to be, however (which may also be a point you're making)...

APU's not only give the plane electrical power when not connected to ground power, but on some jets they provide the power and air necessary to start an engine. Once one engine is started then they can use the power of that engine to start the others. So even if they are connected to ground power, you have to start the APU to crank an engine. Correct me if I'm wrong zaph but the 787 is the same way, no?

And they aren't ordinary generators either. The APU on tankers was inside the jet and it was louder than the damn engines themselves.

reply to post by boomer135


Yeah it's the same for them too. Used to be, way back in the old days, we hooked up air, and blew it through the engine to start it rotating and crank it. Then they'd crank the others from those. We had a start cart that was basically an APU in a box, with a big yellow house that hooked up to the bottom of the aircraft.


*The old days...back when there were E models in the inventory....in the 90s.

reply to post by _Del_


Yes, and yes. I also wouldn't mind taking their money for it.

So far I think our record effective per-hour cost for a major system repair of someone else's design is something like $125,000, which we've done three times but never bettered.

The first time there was an aerospace company Who Shall Not Be Named, was having a pesky issue with avionics, I walked out to the flight line for the walk through, pulled the control board, looked at it, asked if they had a couple more, looked at them, whupped out my tool kit, fixed a solder joint, shoved it back in and hit the 'go' button. Fixed. Time: 15 minutes.

They had a part layout issue that 'shaded' a surface mount passive part in the solder wave, left a joint open consistently. No one caught it for some reason. Thank god we signed the contract before I saw it, I am not sure I could have charged them for it if I'd seen it first. But after, you betcha. You mess with the bull by demanding a fixed amount contract so I couldn't drag the evaluation phase hours out, you got the horns when I fixed it in 15 minutes. That'll be one contract of $30K plus expenses, see you guys at the pool.

"But, you aren't really going to charge us are you?"

"Oh, hell yes. Whose idea was it to make the evaluation a fixed rate?"

"Mine"

"Ok, go back and explain how you will be paying the whole thing. You wanted it, you got it. BTW, we don't pad hours. It's never a good idea to contract us for fixed rate, if you don't like this sort of thing happening"

reply to post by Bedlam


What can I say?

MacDonalds (I'm lovin' it)

Originally posted by Zaphod58
reply to post by boomer135

 

Yeah it's the same for them too. Used to be, way back in the old days, we hooked up air, and blew it through the engine to start it rotating and crank it. Then they'd crank the others from those. We had a start cart that was basically an APU in a box, with a big yellow house that hooked up to the bottom of the aircraft.


*The old days...back when there were E models in the inventory....in the 90s.

edit on 5/23/2013 by Zaphod58 because: (no reason given)

edit on 5/23/2013 by Zaphod58 because: (no reason given)

Now they are our ground A/C carts (Only the Gucci boys ((KC-10)) get A/C on their jets on the ground). Well at least the huge yellow tubes with cold ass air shot up the crew entry chute is what we use in the desert. I've seen temps in the cockpit aproach 150 degrees before in Qatar.

reply to post by boomer135


That was the other use for it during the summer. Then they'd take it down and hook it up to the bottom of the aircraft. Or just run a smaller hose that would also work, and keep the AC until they started 3 and 4, then run the aircraft AC.

Hey zaph have you heard much about the Dreamliner recently ? I have a few friends meant to be flying on it on Thompson airlines who fly from the UK. Is the Dreamliner passenger worthy yet?

reply to post by ThePeaceMaker


Ethiopian and United have started flying passengers with it, with JAL and ANA starting up in the next couple of days. The problems they have now really are teething problems, even though they should have been caught and fixed during testing. I haven't heard of any more problems with any of them flying regular routes though.

Ah damn my friends have been bugging me as they know I have an interest in aviation/planes. "Ooh guess what we are meant to be flying on the Dreamliner" they say, I'm s'n-word'ing to myself thinking "yeh ok if they fix it"
How wrong was I ... Damn them to hell. Thanks for the reply

reply to post by ThePeaceMaker


The first Thomson Dreamliner landed in Manchester at 11am local this morning. It's in a 291 seat configuration, with 47 in Premium, and 244 in Economy. It will enter service in July.

You'd never catch me on one of these damn things as I don't want to die because of"teething problems".I'll pass on that.

Am I a sick puppy for wanting to make up a "cell phone" that emits that special smell of roasting electronics and carry it on one of these things?

Oh, miss, what's that awful smell? I could SWEAR I just saw smoke come out of that panel...

reply to post by Bedlam


I knew there was a reason I liked reading your posts. *lmfao* And no, no you aren't. You just have a warped and sick sense of humor.

reply to post by TDawg61


Every aircraft in existence went through teething problems. The Boeing 777, which today is one of the most popular aircraft out there went through a number of teething problems, and if you take the grounding of the Dreamliner out, it started with a worse dispatch rate than the Dreamliner has. It's since improved greatly, as the Dreamliner will as they figure it out.