APU Use

[hadagutful]

Hello heavy drivers, intending flying to Singapore and was just checking feedback on xxxxxx which interestingly appeared very mixed.
Reviews varied from "excellent airline" to "would never fly with them again" so I guess it can depend on what happens on the particular flight with any airline.
However one comment was relating to a hold up on the ground for about an hour and the passengers were all "sweltering". Pax queried with cabin crew who responded that cannot have air con until start up.
Am I correct in saying that this is nonesense, normally the APU provides air and if not you would have some quite distressed pax especially on a hot day.
Could someone shed light on this, any reason why the APU cannnot be left running for that time or were they saving fuel or something?

[unseen]

Maybe the APU was broken, or was not able to supply bleed air for the aircon.

It happens.

[Angle of Attack]

There is no policy to leave the APU to off until engine start in the airline you mention, in fact if the temperature is above 23 degrees the air con is required to be running, and no boarding if the cabin temp 30 degrees or over. Even with an APU out, an angine would be started on the gate(if no ground air available) and cool the cabin prior to boarding.

[Dora-9]

an angine would be started on the gate(if no ground air available) and cool the cabin prior to boarding. Yeah right - I can immediately think of a couple of major ports where you're not permitted to have an engine running at the gate.

[training wheels]

Do the Virgin ATRs use 'hotel' mode on the ground? Or did they get the option with APU ?

[Capt Fathom]

Yeah right - I can immediately think of a couple of major ports where you're not permitted to have an engine running at the gate
Where and how are you going to start an aircraft without an APU, if you can't start an engine at the gate?

[Dora-9]

Believe it or not Fathom, there are other methods of starting other than using the APU. Many years ago MMA had a "buddy" system (air ducted from another aircraft, e.g. the F.28's as a source for other F.28's or DC-9's - that I saw), more commonly external air is available from ground equipment (carts) and at some airports air is actually available from the terminal itself (e.g. Hong Kong).

The only one of these techniques that involves starting at the bay is using fixed air, and getting a clearance to do that is inevitably quite a performance all in itself...

[nitpicker330]

Ah yes the F28 buddy start!!

These days if the APU is stuffed you'll need to start 1 on the bay unless they can push you and all the ground support equip to a taxyway!! Not likely so start 1 on the bay it is everywhere in the World.

[Capt Fathom]

Actually, starting at the gate not a problem these days. Times have changed. :ok:

[nitpicker330]

Oh, and in HKG there is no compressed air available from the bridge, only Air Con and that sometimes either won't work or is useless!!

So they drive up a truck and plug in compressed air for starting.

[ForkTailedDrKiller]

Flew out of Dallas/FW to BNE last Friday. Apparently the APU on the 747 crapped itself on the way over to the US and was not able to be repaired during the layover. Temps on the ground were over 100+oF. Before we were able to board, one of the main engines was started and run for more than an hour so the cabin could be cooled to a level where boarding could take place. As a result we were more than and hour late in departing.

Mind you, 15 hrs 6 min non-stop from Dallas/FW to BNE is a marvel of my generation!

Dr :8

[rocket66]

Forky,

Just out of curiosity, do the regs have anything to say about a U/S APU and the aircraft not being able to depart from an airport that has services that are able to fix it? Similar to FDR's etc?

Or is it just your usual MEL item for X amount of time??

Rocket

[ForkTailedDrKiller]

Forky,
Just out of curiosity, do the regs have anything to say about a U/S APU and the aircraft not being able to depart from an airport that has services that are able to fix it? Similar to FDR's etc?
Or is it just your usual MEL item for X amount of time??
Rocket Nah mate, the Bo can depart regardless of whether its APU is working or not! :ok:

As for the 747, I wouldn't have a clue - I was in seat 54E !!!! :E

Dr :8

[UnderneathTheRadar]

Forky,

Just out of curiosity


Pretty sure the FTDK wouldn't require the APU repaired during a layover - sufficient (only) cooling obtained by leaving the door open....

UTR - tounge-in-cheek

[Dora-9]

Capt Fathom:

Actually, starting at the gate not a problem these days. Times have changed. Thanks for this - glad to hear this situation has changed for the better. My ears still ringing from abuse for starting on the bay at Singapore in a B744. A long time ago I confess, and my last few years in an airline - also a long time ago now - were on the B777 which came with seemingly the world's most reliable APU....

Cheers!

[Keg]

Rocket66, the MEL for a u/s APU allows for it to be flown for 10 days prior to repair. On twins that may come with a penalty prohibiting flying beyond 60 minutes from an airfield.

[nomorecatering]

Re the DFW/BNE flight........if they run an engine for an hr at they gate they would be about 3000kg short on gas. Can they do hot refueling.

Just curious being such a fuel critical sector.

[Keg]

More like 600kg. Not sure if the 744 can hot refuel.

[hadagutful]

Thanks for responses folks. I guess I shouldn't have mentioned airline concerned but I wasn't out to put them down, I haven't even flown with them.
So who knows what occurred with the APU and the air but I was just making a general query.
It appears that it would be unusual for the cabin not to be cooled or air conned with pax on board.
Not sure what the regs say but I would be surprised if an aircraft so equipped could operate without a serviceable APU.

[nitpicker330]

Well then you'll have to be surprised. !!!

As Keg already has said, most Jets can have an inop APU for around 10 days.
On the A330 it can still do full 180 min ETOPS without one.

Ok :ok:

[Keg]

Not sure what the regs say but I would be surprised if an aircraft so equipped could operate without a serviceable APU.

The regs say you operate the aircraft in accordance with its approved minimum equipment list. The book says you can go sans APU.

Were air con not available and fuel critical to the extent of not being able to run an engine then plan C is needed. Full aircraft, temp in the 30s, and no air would have the temp close to 40 before engine start. Heck, the cabin can be in the high 20s when it's empty, no air and only 20 degrees outside.

[Capt Claret]

Not sure what the regs say but I would be surprised if an aircraft so equipped could operate without a serviceable APU.

The B717 MEL that I operate to allows for no APU for 10days, with certain provisos. Air cart/bottles plus ground power required at each port.

Hot refuelling is only permitted under strict conditions, to get one to a maintenance base, should the APU fall over at an out-port.

As an aside, i've run an engine for air-con during boarding with no issues from the aerodrome operator.

[hadagutful]

Righto keg and Captn Claret et al. Thanks, that clears up my query.

I guess my original worry was hearing that an airline possibly had pax sitting on the ground sweltering without air. An airline would do that at it's own peril I suppose.
There's been plenty of publicity about leaving pets and babies in cars on hot days or any day for that matter and the potential for overheating and even death.
I don't imagine that APU's break down that often anyway.

[tgbgtgb]

More like 600kg. Not sure if the 744 can hot refuel.
It could. Whether its a good idea or not is another question. ;)

[nitpicker330]

If you observe O H and S there would be no physical reason why a 744 or indeed any Jet couldn't refuel on the right side while 1 or even 2 Engines were running on the left side.

Whether operator and or local regs allow for it............another story.

[Checkboard]

We used to hot refuel on the 146 when the APU was U/S.
Arrive on stand
Shut down engines 1,2 & 3 (leave 4 running)
Offload passengers, cleaners get on
Cross-bleed start engine 1, shut down engine 4
Off load & on load bags, hot refuel
Cross-bleed start 4, shut down 1
Cleaners get off, new passengers get on
Cross-bleed start 1,2 & 3 and depart
:ok:

... mind you - a three sector day like that in tropical heat was a loooooong day. :uhoh:

[Capt Claret]

G'day Checkers,

Ansett must've operated the Super 146. Ours had/have electric starters. ;)

G'day to Reddo too.

Hadagutful

There is/was no written guidance in my organisation re boarding with the APU u/s and cabin conditions too extreme. How to manage it seemed to be left to the PIC. Having said that, I've never heard of a PIC having pressure not to run an engine during boarding, even to the point of not commencing until after the baggage (right hand side) loading was complete, to allow the right engine/s to be utilised.

If on an aerobridge, I'd liaise with the ground staff & engineers, and usually start the left engine/s.

[Checkboard]

Shows you how long it's been :p - and as an FO, I didn't get to start engines ;)

Cross-gen start, I guess :)

Reddo would say "hi" - but she's out earning a crust, like a good woman :) She was "ramped" today, as well :ok: