Hydraulic pumps switching during fueling

[FlyinWithoutWings]

Anyone know if there is any restriction on switching On/Off the electric hydraulic pumps while fueling is in progress on the B737 Classics and NGs?

[Krystal n chips]

Non that I can recall re the Classic other than the obvious--ie ensure everybody is clear when you pressurise the system as the L/E devices will clearly retract as you know--and ensure the fuel panel door is secured --obviously. Can't think of any obvious reason why the hyds. should not be selected on / off however given that I certainly witnessed such without any problems. Why the query please?--just curious here.

[Golden Rivet]

There are no specific limitations on switching hyd pumps on during refuelling, although its never a good idea to be switching any systems during refuelling unless you have to.

There is however a minimum fuel quantity for hydraulic operation. This is 760kg in main tanks 1 & 2 for the NG aircraft.

[FlyinWithoutWings]

Krystal-n-chips-
Well- what started the query was the fact that during transits on the 737s, we are invariably doing the transit scan while the fueling is still on. Some Engg. people seem to have a problem with this.
When we ask for hydraulic clearance (for the reason of the the moving LEDS/controls) some of them will go "Capt. the fueling is on".
Asked for why this should be a problem they say "As per the fueling rules avoid any unnecessary power changes/transfers/ or switching."
Now our contention is that what about the other switches .e.g., the fuel pumps themselves (IN the fuel tanks) which could be required to be operated during the fueling itself, or the other systems in the scan.
Now Boeing had a 3 limitatons during fueling
1) Not to start/switch off the Apu during fueling
2) Not to key an HF
3) Not to operate the Wx radar.
If they felt a restriction on the operation of the other systems they would have mentioned it - right? I hope :)

So the choice is either to wait for the fueling to be completed(which takes a while if its a longish flight after our usual transit of 30 mnts) to do your before start scan and hence the checklists or just go ahead and do the scan and cheklists as boeing has not placed any restrictions on the operation of other systems. The fueling rules in the CARS are like ancient and probably need updating. or do they?
:confused:

[FunctionedSatis]

If it not in your ground fuelling manual/handling manual, then theres no reason to not switch them on technically.

But it does make sense not to as the pumps are 3phase ac and draw a large current on start. Also do you want hydraulics live while the fueler is around? hyds make things move as we know.

It may be your company ground fueling manual the engineers use is slighly different to the one you use as flight crew, not the first time i've come accross this.

I think your eng. is just useing common sense, i tend only to allow hyd's on once aircraft footprint is clear of all personnel.

Cheers

Stu

[Blacksheep]

For most of my life in aircraft engineering (40 years now) the aircraft belongs to the maintenance crew until all servicing is complete and the Captain has signed in the log as accepting the aircraft. Its all a matter of safety precautions.

Try working on an aircraft during maintenance and you'd soon appreciate why we don't want systems being operated or surfaces moved while we're going about our business. When we must do these things ourselves as part of the task, we walk around the aircraft, clearing all work areas and warning all staff before applying hydraulic power or moving flaps or control surfaces. Boeing may write the books but they're aircraft builders, not Health and Safety consultants. While we understand the need for fast turn-arounds, there is no justification to reduce safety standards in order to knock a few seconds off here and there.

Its what HSE is all about.

[Popolama]

FlyinWithoutWings said :"

Now Boeing had a 3 limitatons during fueling

1) Not to start/switch off the Apu during fueling <----- Not anymore,this restriction was deleted on a 2004 update

[FlyinWithoutWings]

Popoloma: Thanks.. I stand corrected! 2 limitations now. I do wonder why they changed their mind about the APU? Any ideas?

BlackSheep:

"For most of my life in aircraft engineering (40 years now) the aircraft belongs to the maintenance crew until all servicing is complete and the Captain has signed in the log as accepting the aircraft. Its all a matter of safety precautions"
The flip side is that as a Captain, my period of command (read that as responsibility for the passengers who may be on board during fuelling, the crew, as well as the aircraft), starts from the time I board an aircraft with the intention of flight. We get around to actually signing the log only say 5 minutes to departure when the fueling is complete. Which is why we take clearance from the ground/Maint crew PRIOR to switching on any hydraulics on the aircraft to confirm that nobody is doing any servicing or sticking any parts of themselves into anyplace that might take em off.. etc . So the point of MOVING controls or servicing of the aircraft are obvious and hence addressed when we take clearance. The issue here is specifically FUELING. Would you have a problem with pressurising hydraulics while fueling is in progress and why? Do you think this would reduce safety?

:confused:

[M.85]

NOw,this is interesting...i was told not to start the APU during the refuelling which makes sense..as the battery is used to for the start,hence electrical activity..BUT shutting down is allowed..
PLEASE clarify the matter ..it is very important and please add the specific references if you have them,

Thank a lot,

M.85

[Blacksheep]

No problem with applying hydraulic power while refuelling is in progress, FlyinWithoutWings. What bothers me is the reason for powering hydraulics - presumably to move things; such as flaps & control surfaces. If refuelling is delayed for the usual reason - the crew can't give a final figure until they have the loadsheet - its likely that the area around the aircraft is clear and the only activity is the refuelling; Then there's no problem. When there's the usual bustle of loading baggage and catering, with the area littered with vehicles and equipment, that's when I don't like sudden movements...

I can see your problem of working through a checklist; You reach a point where it says to switch on the hydraulic pumps (obtain clearance) and the servicing crew say no - your checklist comes to a halt. In this case, I say that perhaps the checklist needs a review. Do the pumps really have to be switched on at that point?

I've personally been working on a 737 when the F/O accidentally moved the control wheel while scrabbling about to retrieve a dropped Jeppesen manual. The hydraulics were powered, the ailerons moved and one hit a baggage vehicle reversing out from the aircraft. This resulted in a departure delay while the aircraft was swapped; a case of more haste and less speed. I also know a maintenance man who lost three fingers when an F4 Phantom jockey flipped a switch in the cockpit. Again, more haste, less speed, please.

These twenty five minute turn-rounds that are all the rage with Low Cost Carriers do have a price; Yes, I do think that in many cases, the commotion around the aircraft caused by pressure to shave time off the transit, can reduce safety.

[Krystal n chips]

FWW---I am curious as to why your company stipulates you do a scan / checklists etc during the T/R and not , in the case of control movements for example, after start up and during the taxi out. On a 747, yes I am aware of the "clear to pressurise" etc prior to start, but even then the controls were checked AFTER push back. No reason on a 737 however. Maybe your a review of your company procedures may not go amiss ?

[BOAC]

In my experience over 16 years, part of the external checks in the Ops manuals on the 737's I have flown is a check of the hydraulic systems in the wheel bays for leaks plus a check that the rudder has pressurised 'in-line'. Thus the pumps need to be 'ON' for walk-round which is.....when you are refuelling (on a good day.:D )

[stator vane]

personally, i think hydraulic fluid is a HAZ MAT!

why would i want to have the pumps on whilst i do the walk around.

it would ruin my clothes!!! especially if you're wearing a leather jacket.

(then again it might promote hair growth) though it might be a strange color!

do what the man with the ink pen (checkairman de jour) says!!!!!!!

[FlyinWithoutWings]

M .85 > Will get back to you....

BOAC> Exactly... so how did you guys manage the issue (on the good days:O ) ?

[prop jocket]

Apart form the obvious and previously stated safety concerns regarding moving things with people around the aircraft, which is well orchestrated by the participants involved from my experience, I have a possible reason for discussion.

I'm an engine airframe man by trade, so please allow for a level of ignorance in the finer points of digital electronics.

Could it be that with modern electronics being seriously voltage conscious ( as Messrs Boeing described them on the 747-400 course ) in some applications, any change to electrical load could do disastrous things to totalisers and FQIS equipment, leading to the possibility that the fuel load could be indicated correctly on the gauges, but be incorrect in reality?