Running An APU While Aircraft Is on Jacks???
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Running An APU While Aircraft Is on Jacks???
Hi
Is it possible to run-up an APU while the aircraft is lifted on jacks? (I mean according to the manuals).
-In the aircraft that I am little bit familiar the IDG is cooled by fuel and air (recent engines) and only with air (old engines with CSDs). The fuel that cools the IDG goes to the combustion. It seems that in other aircraft, the fuel that cools the IDG returns into the tank. Is that true?
Feedback appreciated. Thank you.
Best regards
Is it possible to run-up an APU while the aircraft is lifted on jacks? (I mean according to the manuals).
-In the aircraft that I am little bit familiar the IDG is cooled by fuel and air (recent engines) and only with air (old engines with CSDs). The fuel that cools the IDG goes to the combustion. It seems that in other aircraft, the fuel that cools the IDG returns into the tank. Is that true?
Feedback appreciated. Thank you.
Best regards
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Hi Aero Tech
On the various Boeings and Airbusses I work on I cannot think of a "system" reason why you cannot run the APU when the aircraft is on jacks. Although the APU air inlet door position might change into a flight position on some aircraft. If you are in a hangar whilst you do this don't forget the hangar fire detection system. Setting a deluge system off is embarassing!!!!
Your second question about IDG cooling. I cannot think of an aircraft where the IDG is cooled by fuel, as I said my experience is only on Boeings and Airbus. Could you enlighten me on the type you are thinking of?
Rgds Dr I
On the various Boeings and Airbusses I work on I cannot think of a "system" reason why you cannot run the APU when the aircraft is on jacks. Although the APU air inlet door position might change into a flight position on some aircraft. If you are in a hangar whilst you do this don't forget the hangar fire detection system. Setting a deluge system off is embarassing!!!!
Your second question about IDG cooling. I cannot think of an aircraft where the IDG is cooled by fuel, as I said my experience is only on Boeings and Airbus. Could you enlighten me on the type you are thinking of?
Rgds Dr I
I do recall a genius of great local repute who had just finished a major rebuild on a light twin (Chieftan or similar) new engines, props, paint, avionics, etc.
They needed to swing the gear but didn't have the means of powering it up. So he put the aircraft on jacks and started the engines. He managed to make it fall over while the gear was up and wrote off the aircraft, engines, props.
It lay around the back of their hangar for a few years, before they sent to the scrappy! A few months later he came looking for a job, but I declined to offer him employment!
They needed to swing the gear but didn't have the means of powering it up. So he put the aircraft on jacks and started the engines. He managed to make it fall over while the gear was up and wrote off the aircraft, engines, props.
It lay around the back of their hangar for a few years, before they sent to the scrappy! A few months later he came looking for a job, but I declined to offer him employment!
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The only reason that I can think of for NOT running the APU would be a fire risk(assuming the A/C is in the hangar)but would assume it would be okay if appropriate fire trucks were in attendance and adequate ventilation is provided.
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Have a look at any CF6 running around.
Has both a air cooler and fuel cooler for the IDG and PW 4000 has similar...
Aerotech
The fuel used for cooling is never returned to the fuel tank on anything I have worked on.
Has both a air cooler and fuel cooler for the IDG and PW 4000 has similar...
Aerotech
The fuel used for cooling is never returned to the fuel tank on anything I have worked on.
Last edited by Bolty McBolt; 12th Apr 2006 at 10:16.
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APU running while on jacks no drama. You may have to pull a C/B on the APU door but no real problems
Boeing 767 747 can be jacked up to 40 knots and remain on jacks so an APU is not going to give you enough thrust to push it off..
Boeing 767 747 can be jacked up to 40 knots and remain on jacks so an APU is not going to give you enough thrust to push it off..
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got the T shirt
Have completed retaction checks on F406 (turbo twin) using the engines, not starting but motoring over (ie no fuel ign) worked a treat. Had a B747 outside on jacks in Riyadh with APU running as the man said its a 40 knot limit so it never knew the apu was running(they are alive you know only break down in bad weather or when you are trying to leave early.
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PERRIN AGAIN
MUST BE OLD AGE, NOW RETIRED (FLYING IS NOW SAFE). MEANT TO WRITE TWIN TURBINE NOT TURBO AND IT WAS A P&W PT6 FREE TURBINE, SO HOLD THE PROP,
MOTOR THE ENGINE AND BOB'S YOUR UNCLE. SORRY ABOUT THE ERROR. PETER
MOTOR THE ENGINE AND BOB'S YOUR UNCLE. SORRY ABOUT THE ERROR. PETER
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ASFKAP
You are probably correct on the A320 but I have never worked on anything you have to stoop to walk under....
A320.737
In Aus I believe there is a regulation or "order" that specifies no running of engines of any kind inside a hangar....but I could be wrong
You are probably correct on the A320 but I have never worked on anything you have to stoop to walk under....
A320.737
In Aus I believe there is a regulation or "order" that specifies no running of engines of any kind inside a hangar....but I could be wrong
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Hi,
Thank you for your posts.
Dr illitout, I think CFM56's IDG is cooled by fuel and air (737-NG).
Originally posted by Bolty McBolt
[QUOTE]Boeing 767 747 can be jacked up to 40 knots and remain on jacks so an APU is not going to give you enough thrust to push it off.. [/QUOTE
I guess APU can provide a little bit of thrust if operating in flight? what do you think?
ASFKAP, I didn't say you cannot run the APU with the aircraft lifted on Jacks. I was wondering if it is possible: I was thinking if the vibrations (caused by a running APU) MAY affect the position of the aircraft at the aft jack. Since certain aircraft can be jacked up to 40 knots (I don't have access to the AMM, that's why wondering) it seems it is possible to run the APU: may be a wind of 40 knots can cause more vibrations at the tail and aft jack (through the rudder, may be less for elevators).
B 777 is fitted with IDG and BUG (back-up generator). How is the BUG cooled?
Feedback appreciated. Thank you.
Best regards.
Thank you for your posts.
Dr illitout, I think CFM56's IDG is cooled by fuel and air (737-NG).
Originally posted by Bolty McBolt
[QUOTE]Boeing 767 747 can be jacked up to 40 knots and remain on jacks so an APU is not going to give you enough thrust to push it off.. [/QUOTE
I guess APU can provide a little bit of thrust if operating in flight? what do you think?
ASFKAP, I didn't say you cannot run the APU with the aircraft lifted on Jacks. I was wondering if it is possible: I was thinking if the vibrations (caused by a running APU) MAY affect the position of the aircraft at the aft jack. Since certain aircraft can be jacked up to 40 knots (I don't have access to the AMM, that's why wondering) it seems it is possible to run the APU: may be a wind of 40 knots can cause more vibrations at the tail and aft jack (through the rudder, may be less for elevators).
B 777 is fitted with IDG and BUG (back-up generator). How is the BUG cooled?
Feedback appreciated. Thank you.
Best regards.
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NO thrust at all from an apu. NON
Have seen one run up in a trolley stand minor chocking required as most energy is taken from the exhaust gas turning the turbine.
777 bug is cooled by gear box oil..doh
APU running while on jacks....does not effect the aircraft. Running flaps , gear swings and people moving around inside the cabin is a greater source of concern than an APU running.
A 767 and 747 can be jacked in winds up to 40 knots and remain on jacks up to 60 knots.
Not all aircraft are jacked at the tail eg A330 has a nose and 2 wing jacks and a stabilzer jack is put in the tail after jacking but this jack is removed during gear swings etc
A few points for your digestion but I strongly recomend you buy a few text books and have a read..
Have seen one run up in a trolley stand minor chocking required as most energy is taken from the exhaust gas turning the turbine.
777 bug is cooled by gear box oil..doh
APU running while on jacks....does not effect the aircraft. Running flaps , gear swings and people moving around inside the cabin is a greater source of concern than an APU running.
A 767 and 747 can be jacked in winds up to 40 knots and remain on jacks up to 60 knots.
Not all aircraft are jacked at the tail eg A330 has a nose and 2 wing jacks and a stabilzer jack is put in the tail after jacking but this jack is removed during gear swings etc
A few points for your digestion but I strongly recomend you buy a few text books and have a read..
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I was wrong!!!!!! No excuse, other than it was four in the morning!!
737-2/3/4/500 csd/idg air cooled
747-400 RB211 air cooled
747-400 PW air and fuel cooled
757 RB211 air cooled
767 CF-6 air and fuel cooled
777 PW air cooled
777 GE air and fuel cooled
A319/20/21 air and fuel cooled
A330 RR air cooled
A330 CF air and fuel cooled
A330 PW air and fuel cooled
A340-2/300 air and fuel cooled
Three of those I should have known about because I have Cover on them!!
What this goes to prove is:
1. You only retain a part of what you are taught, a small part in my case
2. The CSD/IDG oil cooling system is so damm reliable that I have never had any problems with it in twenty years!
Appologies all round Dr I
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727 APU - not on jacks it won't
IIRC the Boeing 727-200 APU fuel valve was closed by weight off wheels. The APU lives in the (Left ?) wheel well, with intake on Left wing upper surface, and exhaust on right wing upper surface (hence dirty smear on the RHS upper fuse aft of the overwing emerg exits. If F/E forgit to shut down APU on takeoff, it would cut as weight came off wheels (APU not approved for in-flight running for any purpose).
I do not know if there is any workaround for this fuel valve switching (cb pulling etc)
Paul
I do not know if there is any workaround for this fuel valve switching (cb pulling etc)
Paul
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Hi,
Thank you for your posts.
Bolty McBolt, I tought the vibration MAY affect the position of the tail while...
At the beginning I didn't know that the aircraft can be jacked in wind up to 40 or 60 knots (as I said I don't have access to AMM). But as soon as I knew this information (60 knots....) I said the wind of 60 can cause more vibration especially at the tail but yet it is allowed, therefore it is possible to run an APU while the aircraft is lifted.
About the thrust of the APU, again I am not postulating (I said I guess
)
I said a little bit of thrust, because I read that the outflow valve in 737 NG is thrust recovery valve, may be its name implies something (?
) since there is pressure difference between the aircraft and the ambient air especially at cruise.
It will be helpful if someone could give us more information about the meaning of this thrust recovery valve (may be fitted in other recent aircraft)
Feedback appreciated. Thank you.
Best regards
Thank you for your posts.
Bolty McBolt, I tought the vibration MAY affect the position of the tail while...
At the beginning I didn't know that the aircraft can be jacked in wind up to 40 or 60 knots (as I said I don't have access to AMM). But as soon as I knew this information (60 knots....) I said the wind of 60 can cause more vibration especially at the tail but yet it is allowed, therefore it is possible to run an APU while the aircraft is lifted.
About the thrust of the APU, again I am not postulating (I said I guess
)I said a little bit of thrust, because I read that the outflow valve in 737 NG is thrust recovery valve, may be its name implies something (?
) since there is pressure difference between the aircraft and the ambient air especially at cruise.It will be helpful if someone could give us more information about the meaning of this thrust recovery valve (may be fitted in other recent aircraft)
Feedback appreciated. Thank you.
Best regards
