Author Topic: No 2 ECU problem  (Read 107558 times)

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Offline Wizz Kid

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No 2 ECU problem
« on: July 06, 2011, 10:49:00 AM »
For the techies amongst us, though it might be useful to have a topic regarding the No 2 ECU snag which is keeping it on the ground at Waddington.  An unusual fault which I do not recall occurring in my time on the fleet.  :?:
Any feed back from the sooties would be great.
« Last Edit: January 01, 1970, 01:00:00 AM by Guest »

Offline Mayfly

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Re: No 2 ECU problem
« Reply #1 on: July 06, 2011, 10:58:39 AM »
I understand Smiler has just requested a single engine start so hopefully they are getting somewhere [figuratively speaking!!  :lol:  ]
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Offline Thornewhite

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Re: No 2 ECU problem
« Reply #2 on: July 06, 2011, 11:54:39 AM »
Is the ECU on a Vulcan like a car ECU  otherwise I have no Idea what one is can some one explain

I am a car, van, truck mechanic so have an understanding of Veh based problems
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Offline Wizz Kid

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Re: No 2 ECU problem
« Reply #3 on: July 06, 2011, 12:14:47 PM »
ECU stand for "Engine Change Unit".  If you look under the bonnet of your car, the whole engine including the alternator and starter motor would be classed as the ECU.  A new engine for the Vulcan comes minus certain items such as the alternator, constant speed drive unit and starter motor have to be transferred from the old engine to the new one making a new complete ECU ready to be fitted to the aircraft.  Hope this helps.
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Offline Paul Creasey

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Re: No 2 ECU problem
« Reply #4 on: July 06, 2011, 12:19:27 PM »
Hello Thornewhite,
"ECU" in Vulcan terms, is "Engine Change Unit" ie the engine and it's associated ancilliaries.
"ECU" in motor vehicle terms, is (I think) "Electronic Control Unit".
So, not the same thing by any means. I'm NOT a techie, so await a fuller (and perhaps more accurate) explanation by those in the know - who might like to avoid techie jargon in future!
Regards
Paul
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Offline Paul Creasey

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Re: No 2 ECU problem
« Reply #5 on: July 06, 2011, 12:20:58 PM »
Quicker on the draw than me, eh, Wizzie?
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Offline za150

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Re: No 2 ECU problem
« Reply #6 on: July 06, 2011, 12:24:59 PM »
We once had a similar problem on the VC10 Conway. The P3 (compressor discharge) reference signal pipe that comes from the compessor housing had a small ball bearing in a cage that acted as an NRV. The ball bearing in the cage had siezed in its housing and was not allowing P3 reference air to the FCU.

Hopefully it would have been a case of bleeding the fuel system to remove any air pockets. The fuel systems on older jet engines are very sentitive to air in  the system due to the way in which the fuel control units use tiny ammounts of fuel to control the fuel to the engine itself

Not very useful i know but im on my lunch break, will try and explian better when i get home tonight!!
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Offline gurnsy

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Re: No 2 ECU problem
« Reply #7 on: July 06, 2011, 12:27:12 PM »
Building a small altar of jaffa cakes and ale as an offering to the mighty engineers.
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Offline za150

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Re: No 2 ECU problem
« Reply #8 on: July 06, 2011, 12:35:53 PM »
FCU = Fuel control unit
The oylumpus 'FCU' Is called the Chassis mounted fuel system (CMFS)

The CMFS in very much like a Carb (apart from a lot more complex) on a car in the respect that in it uses very little electrics to control the fueling and insted use different refence signals to control the fueling. The reference singals inclued P1 and P3 air (intake and compressor discharge pressure), altitude, Engine speed, OAT Etc in order to give the correct ammount of fuel to the engine depending on what the pilot has asked for (ie where he as the throttles)
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Offline minty4371

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Re: No 2 ECU problem
« Reply #9 on: July 06, 2011, 12:44:20 PM »
Is the unit easy to get at and the problem rectified, or will it involve the engine coming out?
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Offline Wizz Kid

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Re: No 2 ECU problem
« Reply #10 on: July 06, 2011, 12:52:11 PM »
Hi Minty
Presumably you are talking about the CMFS.  This sits on the lower port side of the ECU and comes as an integral part of the unit and is not transferred from old to new.  Complicated to change, but can be done without removing the complete ECU.  

I hope this is not the problem and it is something more straight forward which is affecting the rate of fuel flow to the ECU.
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Offline Fluffy Bunny

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Re: No 2 ECU problem
« Reply #11 on: July 06, 2011, 01:11:29 PM »
So rather than trying to fix the CMFS (if it is the problem) in situ, would it be easier and quicker to do a complete ECU change then let the "sooties" sweat over fixing it out of the airframe?
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Offline Mayfly

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Re: No 2 ECU problem
« Reply #12 on: July 06, 2011, 01:16:21 PM »
I can just see dozens of supporters hastily searching their Haynes manuals..  :lol:
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Offline minty4371

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Re: No 2 ECU problem
« Reply #13 on: July 06, 2011, 01:17:49 PM »
At Wizz Kid
I asked whether the unit that was faulty was easy to get at, or not.  I don't know what is being talked about (I am only a fan of the aircraft).  Apologies for asking the question.  I will keep quiet in the future and not question what is going on.
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Offline Wizz Kid

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Re: No 2 ECU problem
« Reply #14 on: July 06, 2011, 01:18:44 PM »
There is not a lot you can do to the cmfs other than replace it and send it back to the manufacturers for rectification.  There is probably not a replacement item in stock these days so an ECU change would be the better option.  BUT this is a worst case scenario.  Let's hope the problem is much more straight forward
« Last Edit: January 01, 1970, 01:00:00 AM by Guest »