APU (lack of) reliability
APU (lack of) reliability
Is it my imagination, or are APU's surprisingly unreliable? I have lost count of the number of times that I have been in aircraft with an APU that will not start, with a series of knock-on effects, none of which involve abandoning the flight until it is fixed.
I imagine they are rather helpful when you loose all of your engines, so why is such unreliability tolerated? And why does it come about ?
I imagine they are rather helpful when you loose all of your engines, so why is such unreliability tolerated? And why does it come about ?
most airliners today have APU's right down to smallest regional jets and Dash Q400 props
i cannot think of one that doesn't of the top of my head - the last big jets that did not have them were 707 DC8 and VC10 and stuff like early Caravelles and CV990
(RAF fitted apu's to their VC10 )
many airports now do not permit APU's to be run on stand during turnarounds due to noise and other issues
they are extremely reliable and on big ETOPS twins 777 787 330 350 etc they are governed by MEL
many can operate up to high altitudes
Sully of the HUdson fame saved his 320 largely in part that he had his APU on to give him power to for his limited control and instruments
had he not had the APU the outcome would likely not been the same
i cannot think of one that doesn't of the top of my head - the last big jets that did not have them were 707 DC8 and VC10 and stuff like early Caravelles and CV990
(RAF fitted apu's to their VC10 )
many airports now do not permit APU's to be run on stand during turnarounds due to noise and other issues
they are extremely reliable and on big ETOPS twins 777 787 330 350 etc they are governed by MEL
many can operate up to high altitudes
Sully of the HUdson fame saved his 320 largely in part that he had his APU on to give him power to for his limited control and instruments
had he not had the APU the outcome would likely not been the same
I was thinking more of the Trident - one of my first experiences of tin-bashing was working on BEA's replacement of the Artouste with the Garrett GTCP85.
I still love the sound of a pneumatic rivet-gun.
I hadn't realised that, I wonder if the civilian VC-10s also had the Artouste?
I was thinking more of the Trident - one of my first experiences of tin-bashing was working on BEA's replacement of the Artouste with the Garrett GTCP85.
I still love the sound of a pneumatic rivet-gun.
I was thinking more of the Trident - one of my first experiences of tin-bashing was working on BEA's replacement of the Artouste with the Garrett GTCP85.
I still love the sound of a pneumatic rivet-gun.
and yes the first BEA tridents had them under the belly then moved up at the base of the rudder as you know!! and re-worked those
I have been on a couple of BA flights (A319/20) recently where the crew had to apologise that there was no air conditioning on the ground at the gate due to the APU being inoperative.
Which airport were you operating from that they couldn't get a GPU to provide power as a substitute for a failed APU? Or failing a GPU, I'm surprised a modern hub airport didn't have FEGP on the stand which could have provided power.
its for ground electrics only and anywhere you go with a u/s apu then there should be a gpu around or shore power at bigger airports - normally the crew will tell ops to let handling know to have ground power on arrival
True that.
The 787 is the only one I can think of that an extra (3rd) GPU will help with the air con. Even then only one system will run and it will struggle in the heat.
The 787 is the only one I can think of that an extra (3rd) GPU will help with the air con. Even then only one system will run and it will struggle in the heat.
The first time we had a 45 minute slot delay; it was a hot day and the cabin got *very* sticky.
It happened again last week, but we weren't delayed so it wasn't so much of an issue.
It was Schiphol on both occasions. I assume we were plugged into a shore supply but that only provided very minimal ventilation. I believe they can also use an external conditioned air supply and avoid having to run the APU on the stand, but for some reason that wasn't available.
The first time we had a 45 minute slot delay; it was a hot day and the cabin got *very* sticky.
It happened again last week, but we weren't delayed so it wasn't so much of an issue.
The first time we had a 45 minute slot delay; it was a hot day and the cabin got *very* sticky.
It happened again last week, but we weren't delayed so it wasn't so much of an issue.
sadly with no apu we go back to the dark ages when stuck on board on a hot day
My most recent experience was on arrival in NBO. We were told that they couldn't shut down the engines because the APU was u/s and they couldn't attach the airbridge until the engines were shut down. So would we please sit tight while they worked that one out.
they could have attached a GPU immediately on stand with chocks in though but I suppose the airbridge had built in shore power?
Are they inherently unreliable or maintained to a lower standard than jet engines? (Maintenance costs money and they are less safety critical than engines.)
Quite a high proportion of the BA747s I've been have had faulty APUs and judging by the number of air start units I;ve seen around its not just a BA problem.
I was delayed for over 30 mins at Toronto a couple of years ago as the ground start unit couldn't get the RB211 going on its own and they had to get a second to help out. I've seen calculations for the cost of delays, though I'm not entirely sure I believe them.
As a matter of interest could some techie tell me:
- What is the main problems, presumably like the engines its the things that hang on the APU rather than the turbine itself?
- if the APU were on the MEL (I knows its not) and despatch critical could you complete a typical repair in a 2 hr turnaround?
- are there spares pools around the world for APU components?
Quite a high proportion of the BA747s I've been have had faulty APUs and judging by the number of air start units I;ve seen around its not just a BA problem.
I was delayed for over 30 mins at Toronto a couple of years ago as the ground start unit couldn't get the RB211 going on its own and they had to get a second to help out. I've seen calculations for the cost of delays, though I'm not entirely sure I believe them.
As a matter of interest could some techie tell me:
- What is the main problems, presumably like the engines its the things that hang on the APU rather than the turbine itself?
- if the APU were on the MEL (I knows its not) and despatch critical could you complete a typical repair in a 2 hr turnaround?
- are there spares pools around the world for APU components?
Are they inherently unreliable or maintained to a lower standard than jet engines (maintenance costs money and they are less safety critical than engines)?
Quite a high proportion of the BA747s I've been have had faulty APUs and judging by the number of air start units I;ve seen around its not just a BA problem.
I was delayed for over 30 mins at Toronto a couple of years ago as the ground start unit couldn't get the RB211 going on its own and they had to get a second. I've seen calculations for the cost of delays, though I'm not entirely sure I believe them.
As a matter of interest could some techie tell me:
- What is the main problems, presumably like the engines its the things that hang on the APU rather than the turbine itself?
- if the APU were on the MEL (I knows its not) and despatch critical could you complete a typical repair in a 2 hr turnaround?
- are there spares pools around the world for APU components?
Quite a high proportion of the BA747s I've been have had faulty APUs and judging by the number of air start units I;ve seen around its not just a BA problem.
I was delayed for over 30 mins at Toronto a couple of years ago as the ground start unit couldn't get the RB211 going on its own and they had to get a second. I've seen calculations for the cost of delays, though I'm not entirely sure I believe them.
As a matter of interest could some techie tell me:
- What is the main problems, presumably like the engines its the things that hang on the APU rather than the turbine itself?
- if the APU were on the MEL (I knows its not) and despatch critical could you complete a typical repair in a 2 hr turnaround?
- are there spares pools around the world for APU components?
Join Date: Jan 2013
Location: Right hand seat of a 777
Posts: 168
Likes: 0
Received 0 Likes
on
0 Posts
I seem to recall in my youth, that we used to joke that the A340-300 had 5 APU's, 4 on the wings and 1 in the tail made 5. Can't remember much reliability issues with them
OMAA
OMAA
