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Search: Posts Made By: bsieker
Showing results 1 to 35 of 47
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Forum: Rumours & News
22nd Mar 2009, 16:34
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Just to get the facts straight. Idle fuel flow is...

Just to get the facts straight. Idle fuel flow is less than 1,000pph (see first AAIB interim report, p.4, second paragraph), at which flow rate the difference between counter- and concurrent flow...
Forum: Rumours & News
22nd Mar 2009, 00:08
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Not knowing, as we assume the designers did not...

Not knowing, as we assume the designers did not know, that ice may be a problem, the question is: why not?

The fuel delivery system, including pumps, filters, and the path through the FOHE is...
Forum: Rumours & News
21st Mar 2009, 22:45
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Sorry, that is thermodynamical nonsense. If...

Sorry, that is thermodynamical nonsense.

If the fuel would be getting warmer, it would mean that more heat (energy) was transferred to the fuel. All energy that is transferred to the fuel, must...
Forum: Rumours & News
19th Mar 2009, 16:14
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Why is this?[/QUOTE] Basic thermodynamics,...

Why is this?[/QUOTE]

Basic thermodynamics, really.

Ideally, a countercurrent flow HE can make the "hot" fluid (oil) at its exit almost as cold as the "cold" fluid (fuel) at its inlet (when it...
Forum: Rumours & News
19th Mar 2009, 08:54
Replies: 3,239
Views: 1,137,419
Posted By bsieker

No, the rate of heat exchange has been designed...

No, the rate of heat exchange has been designed the way it is. Having more heat exchanged may make the oil too cold. The other name for the FOHE is "Fuel Cooled Oil Cooler", which clearly states is...
Forum: Rumours & News
13th Mar 2009, 13:07
Replies: 3,239
Views: 1,137,419
Posted By bsieker

A very interesting point, which we have also been...

A very interesting point, which we have also been discussing on a closed mailing list. Two possibilities spring to mind:

1- There have been some previous incidents, but all happened at altitude,...
Forum: Rumours & News
12th Mar 2009, 16:06
Replies: 3,239
Views: 1,137,419
Posted By bsieker

airfoilmod, sorry for being obscure. ...

airfoilmod,

sorry for being obscure.

You said in your post that both actions (max. thrust, and idle thrust) were to avoid ice build-up.

They aren't.

One was supposed to avoid it, the...
Forum: Rumours & News
12th Mar 2009, 14:53
Replies: 3,239
Views: 1,137,419
Posted By bsieker

To avoid the ice buildup, max climb thrust for...

To avoid the ice buildup, max climb thrust for step climbs had been mandated a couple of months ago in certain cold conditions.

This has proven to be insufficient in some cases. The Delta flight...
Forum: Rumours & News
13th Aug 2008, 14:02
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Diversity / Dissimilarity

DozyWannabe, Pacplyer, VnV, others, ...

This is about the B777's FBW system (more specifically, the PFCs).

The approach of having three separate coding teams, isolated from each other, was...
Forum: Rumours & News
12th Aug 2008, 10:14
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Herc708, This hardly merits an answer, I...

Herc708,

This hardly merits an answer, I think DozyWannabe got it right.

Your rant has absolutely nothing to do with real-time safety-critical embedded systems development. To start with, such...
Forum: Rumours & News
8th Aug 2008, 14:40
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Yes, that's what I was trying to say with my...

Yes, that's what I was trying to say with my remarks that high-reliability in software cannot be shown by testing. The argument can be made for mechanical backup, but also for better software...
Forum: Rumours & News
8th Aug 2008, 10:39
Replies: 3,239
Views: 1,137,419
Posted By bsieker

TechnoFreak, Yes. One minor correction:...

TechnoFreak,

Yes.

One minor correction: The cavitation damage was on the outlet side of the HP pump. Which is to be expected, as, although low pressure in the inlet makes the bubbles form, the...
Forum: Rumours & News
8th Aug 2008, 08:55
Replies: 3,239
Views: 1,137,419
Posted By bsieker

pacplayer, no offence intended, maybe my...

pacplayer,

no offence intended, maybe my words were a bit harsh.

With cooler head:

I assumed you were talking about fly-by-wire since you specifically mentioned Airbus and B777, which are...
Forum: Rumours & News
7th Aug 2008, 17:36
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Well, that is the $500m question, is it not? ...

Well, that is the $500m question, is it not?

Could it perhaps be the reason why there has been no further word from the AAIB/Boeing/Rolls Royce? They haven't figured it out yet.



FADEC is a...
Forum: Rumours & News
23rd Jul 2008, 09:08
Replies: 3,239
Views: 1,137,419
Posted By bsieker

As all accidents, it had a number of causal...

As all accidents, it had a number of causal factors. Never only one single cause.



Fuel temperature:


And:
Forum: Rumours & News
18th Jul 2008, 14:38
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Chris Scott has already speculated about what a...

Chris Scott has already speculated about what a similar scenario would look like in the A330. It's an interesting read...
Forum: Rumours & News
9th Jun 2008, 15:56
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Thanks for the pointer to the docket, it's an...

Thanks for the pointer to the docket, it's an interesting read.

However, I don't see its relevance to BA 038.

According to the AAIB's reports ...



So, no suction feed.
Forum: Rumours & News
19th May 2008, 06:49
Replies: 3,239
Views: 1,137,419
Posted By bsieker

airfoilmod, apologies for the misleading...

airfoilmod,

apologies for the misleading wording.

There are two pumps in the engine, one low pressure, that ensures uninterrupted feed to the high-pressure pump, and often, as shown in the...
Forum: Rumours & News
18th May 2008, 15:09
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Thanks for the link! These are the boost...

Thanks for the link!

These are the boost pumps, sucking directly from the tanks, located in the wings, and supplying positive pressure to the fuel manifolds.

There are in fact 7 such pumps, two...
Forum: Rumours & News
14th May 2008, 08:05
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Yes, it has indeed been covered on this thread....

Yes, it has indeed been covered on this thread. And in quite some detail, complete with drawings. And yes, fuel is drawn from the tank low point (duh!), but no, gravity-feed or suction-feed is not...
Forum: Rumours & News
13th May 2008, 20:46
Replies: 3,239
Views: 1,137,419
Posted By bsieker

(my emphasis) Interesting theory. However,...

(my emphasis)

Interesting theory. However, where I live, it is unheard of.

A few remarks.

1/ With the boost pumps working, the fuel manifold is under positive pressure. There is no suction...
Forum: Rumours & News
13th May 2008, 11:52
Replies: 3,239
Views: 1,137,419
Posted By bsieker

tanimbar, Thanks a lot for your post. It was...

tanimbar,

Thanks a lot for your post. It was interesting reading. I'd like to comment on a few minor points.

(my emphasis)

To be nitpicking, the AAIB quoted the meteorological services as...
Forum: Rumours & News
13th May 2008, 09:19
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Mass Flow Transmitters

hetfield,

thanks a lot.

I've been reading up a little and it appears that due to the widely varying temperatures (I'd reasonably expect somewhere between +40 and -40 degrees C) and densities of...
Forum: Rumours & News
13th May 2008, 08:28
Replies: 3,239
Views: 1,137,419
Posted By bsieker

How does that follow? If fuel were foaming per...

How does that follow? If fuel were foaming per earlier comments, measured flow would remain low, fuel energy would remain low, and a quick reversal of that condition would not be possible because...
Forum: Rumours & News
13th May 2008, 06:26
Replies: 3,239
Views: 1,137,419
Posted By bsieker

APU Fuel Path

The APU is fed from the left engine fuel manifold, which is supplied by either left boost pump (main tank aft, main tank forward, center tank left), or by an additional DC pump in the left main tank....
Forum: Rumours & News
12th May 2008, 20:30
Replies: 3,239
Views: 1,137,419
Posted By bsieker

No Evidence

As usual, the AAIB chose the words very carefully. The report says there was no evidence of EMI, core icing, electronics or systems malfunctioning.

But since no evidence whatsoever of what went...
Forum: Rumours & News
12th May 2008, 20:05
Replies: 3,239
Views: 1,137,419
Posted By bsieker

New Special Bulletin.

Today the AAIB issued a new Special Bulletin (http://www.aaib.gov.uk/latest_news/special_bulletin_s3_2008.cfm), updating information of previous reports.

Of note:

- No evidence of:
. EMI
...
Forum: Rumours & News
7th May 2008, 08:50
Replies: 3,239
Views: 1,137,419
Posted By bsieker

I agree that it is a likely scenario, and it fits...

I agree that it is a likely scenario, and it fits the rest of the scenario just fine, an upstream fuel flow restriction, causing both pump cavitation and restricted flow (the former possibly...
Forum: Rumours & News
6th May 2008, 17:29
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Cavitation, again.

Not so. Although the AAIB report mentions cavitation signs on the HP pump outlet, it is by no means clear that this damage was caused by an event immediately preceding this accident.



The...
Forum: Rumours & News
4th May 2008, 20:42
Replies: 3,239
Views: 1,137,419
Posted By bsieker

It may be that compressor stalls can manifest...

It may be that compressor stalls can manifest themselves in a way that the engine first accelerates and then rolls back. And also that it may happen on both engines at nearly the same time.

But...
Forum: Rumours & News
3rd May 2008, 21:55
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Oluf Husted, the problem with that theory is...

Oluf Husted,

the problem with that theory is that the engines did spool up, initially, until fuel flow reduced.

And I am still curious exactly which behaviour of BA038 you describe as...
Forum: Rumours & News
2nd May 2008, 16:47
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Summary

Summing up the answers to some recurrent ideas, and also some (seemingly) new ones.

1/ Mr. Spaz "outagaz" Modic

L337, regarding Spaz Modic, I might just say, "Please don't feed the Troll".
...
Forum: Rumours & News
24th Apr 2008, 21:05
Replies: 3,239
Views: 1,137,419
Posted By bsieker

mark exclamation, I don't know if there's...

mark exclamation,

I don't know if there's really a new twist.

Core icing in high-bypass turbofan engines has lately been the subject of some discussion, such as this PPRuNe thread...
Forum: Rumours & News
11th Apr 2008, 07:57
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Without double checking I believe you have...

Without double checking I believe you have overlooked two points.

1. The word INDICATED was used.
2. No statement as to where the indicated fuel was stored. i.e. Wing Tanks or CWT. The fuel...
Forum: Rumours & News
2nd Apr 2008, 21:24
Replies: 3,239
Views: 1,137,419
Posted By bsieker

Yes. The figures look reasonable; at the...

Yes.

The figures look reasonable; at the minimum fuel scavenge rate of 400kg/h, it would take 2 hours, 15 minutes to scavenge all of the 900kg from the center tank. It would have finished some 45...
Showing results 1 to 35 of 47
 
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