Hydraulic pumps- on or off during turnaround??

[blue belly]

Does anyone have experience at leaving hydraluic pumps on during a turn around on B757 B767 acft? I believe it is sometimes done on B737 acft?

What about fuel pumps during a turn around?

Turn around = less than one hour...

Can you pls advise your experiences? thks!

[RMC]

737 NG & Classic.If strong winds will leave one electric hydraulic pump on after engine shutdown to avoid possible damage to flying controls.

[hetfield]

737 NG & Classic.If strong winds will leave one electric hydraulic pump on after engine shutdown to avoid possible damage to flying controls.

:bored:
What about night stops?

[Blip]

We've been advised by our technical dept that the flight controls can not be damaged by wind. Apparently there is enough dampening effects in the control system to prevent that from happening.

However because the B737 has Manual Reversion (direct cable link between the control wheel/column and ailerons/elevators, it's good to leave the hydraulics pressurised during turn arounds in windy conditions to prevent the control column from moving about between your legs. (The ailerons aren't usually the problem, it's the elevator flapping up and down with tailwinds causing the control column to move backward and forwards that's the problem.)

If it's the last flight of the day and there's a moderate wind blowing from behind the aircraft, I just leave it to the engineers to shut the hydraulics down after they've done their overnight checks. If I was securing the aircraft at a non-maintenance airport and it was windy, I would wait until I was out of my seat before shutting the hydraulics off.

[rubik101]

On a turn around, leave them all on. Hydrauilic and Fuel pumps.
Last flight of the day, all off.

[Mach E Avelli]

By keeping hydraulic pumps on you have a better chance of spotting any leaks on the walkaround and you reduce risk to ground personnel (slats droop with them off, so you then have the hassle of getting a clearance to re-pressurize). Fuel pumps? Engineers tell me they don't seem to have any less life if they run continuously, so you may as well leave them on (main tanks only!). One less thing to forget at start-up. KISS. I am talking B737 classic - no idea for 767, but am guessing same basic reasons for leaving it all in go position.

[Old Fella]

As a retired F/E I find it interesting that you guys would even suggest leaving the hydraulics pressurised and the fuel pumps running during ground time. Fuel pumps do have a finite life and running them whilst they are not feeding an engine is certainly not good practice in my view. Some of you may recall a Phillipine Airlines B737 burning on the ground in the late '80s at Manilla. Running CWT pumps without fuel in the tank was cited as the cause. As for hydraulics being kept pressurised during turnarounds it is simply dangerous. I am darn sure there is a very good reason for getting a clearance from your friendly ground engineer before pressurising hydraulics whilst ground personnel are moving around the aircraft. I know I wouldn't be sticking any part of my body in a wheel well or near any hydraulically powered component without knowing that (a) the system is depressurised or (b) if it was pressurised I was in contact with the cockpit. Quote: "One less thing to forget at start-up" in relation to these issues. You have got to be joking! :ugh:

[OutOfRunWay]

On my outfit, hydraulics depressurized.

I hate to think of a ground engineer putting a screwdriver to some component, only to have it propelled out of his hand and through his skull by 3000psi. (and, to add insult to injury, being hosed down by fluid, although he might not care anymore)


yuk. OORW

[Denti]

On groundstays with less than 60 minutes planned hydraulics and fuel pumps (main, not center) have to stay on as per Boeing recommendation (737 classic and NG). Our engineers know that and they are not allowed to just walk up to the aircraft and stick a screwdriver into parts without visiting us chaps in the front office first and make sure everything is as they want it and we are briefed as how systems have to be configured during whatever maintenance they do. Otherwise the risk that we don't even notice they're there is way too big.

[cptpilot737]

İf it is not the last flight of the day, We leave the hydraulic pumps On, Fuel pumps Off ( except one main tank pump for the APU ). 737-800

[out_sider]

E145 hydraulics OFF during turnaround.

We have a gustlock for the elevator so no worries there, but the rudder and ailerons are free to flap about. In my experience however, they dont. Both are reasonably stiff in what is essentially the manual reversion mode.

Of course, we should all be following the company Ops Man and FCOM when it comes to this :ok:

[OutOfRunWay]

Does Boeing give a reason as to why fuel and hydraulics should remain pressurized? As stated previously in the thread, possibly to stop control surfaces flapping in the wind? (Although ive never seen that on the 'bus)

OORW

[smudgethecat]

Blue belly ,i cannot really see any good reason why you would wish to have the boost pumps and hyd pumps running during a turnround, whats the point ? as well as being a major safety issue theres wear and tear on the pumps, plus extra load on the APU to consider, (not to mention the bloody racket those AC hyd pumps make).
We look after a fair few 757/767 operators apart from our own A/C and ive never known any crews to leave the pumps on as a matter of routine

[Old Fella]

Denti, I would be interested to see a copy of the Boeing recommendation that hydraulics be kept pressurised and main tank fuel pumps be kept running during turnarounds of less than 60 minutes duration. Frankly, I believe it is a load of rubbish and as Smudgethecat asks, what reason is given by Boeing?

[Toujours]

On groundstays with less than 60 minutes planned hydraulics and fuel pumps (main, not center) have to stay on as per Boeing recommendation (737 classic and NG).


Main, not center. Is this poster referring to the main fuel pump? If so, why the main and not the centre?

[rubik101]

Taken directly from the Boeing FCOM
Very clearly, Hydraulic and Fuel pumps remain ON during transit stops.
Centre tank pumps will remain ON if fuel is present.


737 Flight Crew Operations Manual
Normal Procedures -
Amplified Procedures
Copyright © The Boeing Company. See title page for details.
1 Jun 2007

Transit Shutdown Procedure - Pilot Flying
After the airplane has come to a complete stop, perform the following
actions:
Parking brake ............................................................ ................... Set
Parking brake warning light – Illuminated
Electrical ............................................................ ..................... On___
Verify APU powering busses. If APU is not to be used, connect
external power.
Start levers...................................................... ........................CUTOFF
If possible, operate the engines at idle for three minutes prior to
shutdown to thermally stabilize the engine hot sections. Operating
times at or near idle, such as taxiing before shutdown, are applicable
to this three–minute period. If operational requirements dictate, the
engines may be shut down with a one–minute cooling period.
FASTEN BELTS switch ............................................................ ....... OFF
PA (captain) ..................................... “DISARM SLIDES AND OPEN DOORS”
ANTI COLLISION light switch .......................................................... OFF
At 20% N2 place the ANTI-COLLISION light switch OFF.
WING and ENGINE ANTI–ICE switches .............................................. OFF
Air conditioning PACK switches...............................................As required
APU fuel flow is reduced with both pack switches off.
ISOLATION VALVE switch – OPEN
APU BLEED air switch...................................................... ............... OFF
Exterior lights ............................................................ .........As required
Cockpit door........................................................ .....................Unlock
The PF calls “TRANSIT SHUTDOWN CHECKLIST.”

[rubik101]

Just to clarify, to those of you who will say that the above post doesn't specifically say anything about the pumps in question, I add the following which should answer the questions raised. It also answers the question regarding HYD pumps in windy/gusty conditions.

737 Flight Crew Operations Manual
Normal Procedures -
Amplified Procedures
Copyright © The Boeing Company. See title page for details.

1 June 2007

Shutdown Procedure - Pilot Flying
After the airplane has come to a complete stop, perform the following
actions:
Parking brake ............................................................ .................... Set
Parking brake warning light – Illuminated
Electrical ............................................................ ..................... On___
Verify APU powering busses. If APU is not to be used, connect
external power.
Start levers ............................................................ ................CUTOFF
If possible, after high thrust operation, including reverse thrust, run
the engines at or near idle for three minutes before shutdown to cool
the engine hot sections. Time at or near idle, such as taxiing before
shutdown, is applicable to this three minute period. If needed, the
engines may be shut down with a one minute cooling period. Routine
cool down times of less than three minutes before shutdown are not
recommended.
FASTEN BELTS switch...................................................... ...............OFF
PA (captain) .........................“DISARM SLIDES AND OPEN DOORS”
ANTI COLLISION light switch ...........................................................O FF
At 20% N2 place the ANTI-COLLISION light switch OFF.
FUEL PUMP switches ............................................................ ..........OFF
CAUTION: Do not operate the center tank fuel pumps with the
flight deck unattended.
GALLEY power switch (as installed) ......................................... As required
WINDOW HEAT switches ............................................................ .....OFF
WING and ENGINE ANTI–ICE switches ................................................OFF
ELECTRIC HYDRAULIC PUMP switches ............................................... OFF
CAUTION: To avoid unwanted control column movement during
gusty tailwind conditions, leave the B electric
hydraulic pump switch ON until completing the
Secure procedure.
RECIRCULATION FAN switches ........................................................AUTO
Air conditioning PACK switches.................................................As required
APU fuel flow is reduced with both pack switches off.
ISOLATION VALVE switch – OPEN
Engine BLEED air switches ............................................................ .....ON
APU BLEED air switch...................................................... ................ OFF
Exterior lights ............................................................ ..........As required
AUTO BRAKE select switch ............................................................ .. OFF
Flight deck lights ............................................................ .......As desired
SPEED BRAKE lever ............................................................ DOWN detent
Parking brake ............................................................ ....................SET
It is not necessary to release the parking brake after the chocks are in
position, unless the captain is of the opinion that the brakes are
unusually hot, then only for 5 to 10 seconds and reset the parking
brake. Inform engineering/services if hot brakes are suspected.
Cabin door ............................................................ .....................Unlock
The PF calls “SHUTDOWN CHECKLIST.”
The PM accomplishes the SHUTDOWN checklist.
CAUTION: To avoid the possibility of shoulder harness buckles
snapping back and pulling or damaging circuit
breakers, hold both straps before releasing and then
allow straps to retract slowly to the stowed position.
IRS mode selectors................................................... ...................................OFF
CAB/UTIL, IFE
GALLEY POWER switches (as installed) ................................... As required
EMERGENCY EXIT lights switch ........................................................OFF
Air conditioning PACK switches ........................................................OFF
Trim air switch ............................................................ .................OFF
APU switch/GROUND POWER switch..................................................OFF
If APU was operating:
Delay approximately 2 minutes after the APU GEN OFF BUS
light extinguishes before placing the BATTERY switch OFF.
BATTERY switch ............................................................ ..............OFF
The PF calls “SECURE CHECKLIST.”
The PM accomplishes the SECURE checklist.

End of discussion, or is it?

[Denti]

Main, not center. Is this poster referring to the main fuel pump? If so, why the main and not the centre?

Center fuel pumps only if we have more than 2300kg of fuel in the center tank (NG) or more than 453kg (classics) and if they are on we have to have personnel on the flightdeck at all times to check for low pressure lights. Since we usually don't have to tank that much we don't do that very often.

[blue belly]

we are looking at revising our flight procedures and I just was interrested to know what the standard procedures are from other airlines who also operate 757/767.. and of course 737s.

thks for your replies- keep em coming!

[smudgethecat]

Actually its not i suspect the end of the discusion, as the OP was asking about the 757/767 not the 737,... any 757/767 crew care to comment

[Centaurus]

737 Flight Crew Operations Manual
Normal Procedures -
Amplified Procedures
Copyright © The Boeing Company. See title page for details.

1 June 2007

Are you sure the items published as FCOM procedures are exactly Boeing and nothing else added? Seems to me a fair amount of company initiated material added when compared with the "original" untainted Boeing FCOM?

[luvly jubbly]

On the 73s I used to fly; Electric hydraulic pumps off. All fuel pumps off except for fwd left if req for apu.

For 757/767; all fuel pumps off, hydraulic pumps off (except engine driven pumps).

http://www.b737.org.uk/nnp.htm

http://www.757.org.uk/sops/sop9.html

[rubik101]

As has quite rightly been pointed out, many, if not all FCOMs are indeed altered to accommodate each airline's peculiar requirements.
They are however, submitted to Boeing to obtain a 'No Technical Objection' certificate from their Flight Ops dept.
The procedures quoted above reflect a turn around on a multi sector day, 4 to 6 flights, with minimal wasted time on the ground. The 'Secure' checklist is used at the end of the day after the last flight.
The greatest wear on any pump, be it electric or hydraulic, is that incurred during start up. Multiple starts causes far more wear than constant running.

[Mr.Brown]

The 757 and 767 have much better indications on their hydraulic systems than the 737CL at least.
The 737CL has no flight deck indication of the reservior pressure therefore I would check the reservior pressure in the wheel well, before running the electric pumps on the ground, with no bleed air on, to avoid cavitating the pumps..:ok:

[rubik101]

Why would running a pump with no accumulator pressure cause it to cavitate? Even if the accumulator pressure is zero the pumps will still pressurise quite safely. The accumulator is downstream from the pump.

[smudgethecat]

I think your getting confused between accumulator pressure and resv header pressure rubik , two very different things.

[blue belly]

I'd really appreciate to hear from some 757/767b operators- any out there?

[Old Fella]

Rubik101, thank you for the checklists, however I still wonder at the reasoning.

[BOAC]

Cannot help 'blue belly' with the 75/6, but it is common practice on the 737 to have the pumps on for the walk-round to check for leaks etc and rudder position. It then becomes a practical matter of 'how long before next the walk-round' and 'how long before we do the cockpit prep' for the next sector as to whether they go off in the shut-down or stay on. EG - I suspect Ryanair don't bother to turn them off. I don't on t/rounds of less than 45 mins, when I'm normally out of the seat PDQ, with fuelling, finding the agent, checking my bag has not been off-loaded in bongo-bongo land and beating the next rain shower in mind.:)

[rubik101]

Smudge, you are quite right, however, the reservoir does not need to be pressurised with bleed air before the HYD pumps are run on the ground. The positive air pressure is to prevent foaming when at high altitude.

[CEJM]

Rubik101,

Sorry, but you are partially wrong. The hydraulic reservoir needs to be pressurized before running the pumps on the ground.

Unfortunately, I can not copy the info into this topic (no idea how to do it :{) but in the B737 Maintenance Manual it clearly states that you have to pressurize the system before running the pumps.

[rubik101]

CEJM, are you saying that the HYD pumps cannot be run on the ground unless the APU is running and the bleed system pressurised?
If you are, it's news to me and I have flown the 737 for over 20 years.

[Denti]

Nothing in our FCOMs about that as well. No requirement to pressurize the reservoirs first, neither in classics nor NGs.

[Back Seat Driver]

re 737, long time since I flew one and am happy to be corrected, but I think the HYD pump switches require electric power to turn and maintain the HYD pump off (unpowered the pumps will be on by default). This makes no difference when the aircraft is put to bed for the night, except isn't it then redundant to turn the electric hydralic pumps OFF once electrical power is removed from the busses.

[stilton]

The potential safety aspects of injuring ground personnel outweigh any other
reason to leave (especially) hydraulic pumps on during any turn around.

[aerostatic]

737 Flight Crew Operations Manual
Normal Procedures -
Amplified Procedures
Are you sure you are using a completely Boeing standard FCOM? It doesn't look like it to me. Many companies pay Boeing good money to incorporate their own SOP's into the Boeing FCOM.

Edit: Sorry I see Centaurus has already queried this.

[CEJM]

rubik101, we miht have crossed wires at the moment.

Before running the hydraulic pumps the reservoir has to be pressurized. However this does not mean that the APU has to be running and the bleed system to be pressurized.

During maintenance we have to release pressure from the hydraulic reservoir by means of an depressurization valve. This will remove all pressure from the reservoir. After this has been done you need either bleed air to provide pressurization or an external air supply. Runnig the pumps without the tank pressurized increases the risks of cavitation.

In normal day to day operation of the aircraft the pressure on the hydraulic system should be maintained be a check valve in the pressurization module.

So for a pilot, as long as the tanks have not been depressurized by maintenance you can run the pumps on the ground without the APU or the bleed system pressurized. However may the system have been depressurized by maintenance or a faulty check valve then the system needs to be pressurized before runnig the pumps.


Leaving the hydraulic pumps running on the ground (when not required) is bad practice and puts people in danger. Yes, I agree you will be able to see a leak quicker. However, several times in my career we had such a small leak which was only evident by a fine mist in the wheelwell (and declining quantity indication in the flight deck). So the poor bugger going into the wheelwell has the hydraulic fluid all over them. Not a good practice and something which should be avoided.

[smudgethecat]

Getting back to the original post which refered to the 757/767, i had a look at the 757 FCOM last night and it clearly states the hyd pumps and the boost pumps should be selected off, so perhaps that settles it (or maybe not):)

[blue belly]

Getting back to the original post

Thks Smudgethecat- some companies do things which are not manufacturer SOP, and I am wondering if there are some 757 or 767 operators who do leave the pumps running during turn arounds.

[smudgethecat]

Hi BB, maybe there are, however as i said previously we look after a fair few 757/767 operators from a variety of countries and ive never known any crews carry out this procedure, i cannot really think of any reason why you would wish to do so , however you never know

[blue belly]

Hi,

Thks for all your replies- it was just a point to look at in regard to MFF with 737/757/767...