Continue to destination with loss of one hydraulic system

[davinchi]

Hello,

I am quite new to the boeing 737NG. With a loss of hydraulic system A OR B would you continue to your destination or land at your departure airport? I am looking at this from a simulator point of view, on the line I would contact company. I also realise that shortly after take off with loss of B you would have to return to the airport of departure. My thinking is if I lost hydraulic system A I would be inclined to continue as this would burn off more fuel and lower your landing weight at the other end, which would be beneficial as you have no ground spoilers upon landing. My logic seems sound just posting to check that I have not missed something obvious.

[BOAC]

You need to be aware of where the fluid went and why the system failed too, but there is no need to 'return' to departure. While it may be the most sensible in terms of weather, fuel, maintenance etc etc, flight could perhaps continue either to destination or a more suitable diversion airfield if conditions are suitable. Obviously your max altitude is limited and drag is higher with the LEDs out so care is needed, and you are, unfortunately in 'uncharted territory' as far as the FMC fuel predictions are concerned, so it is back to a 'how-goze-it' chart on the back of that well-know fag packet. Likewise with sys A - there may be good reasons to 'return' - and not.

Especially in the sim (Sys B), if everything else looks ok, I would tend to continue en route at a lower level while you carefully and thoroughly exercise any one (or more) of the 20 or 30 different favourite 'problem analysis' catchphrases. :). That will also give you a bit of space to rebrief a return - if that is your ultimate decision - without being 'rushed', plus a nice measured 'NITS' brief and perfect pax PA:). Don't forget to try your 'synthetic' calls to company for 'ops/engineering' advice as well for max brownie points but beware the 'gotcha' reply you may be thrown - it must be your/Captain's decision in the end.

[davinchi]

Thanks BAOC,

I found that very helpful.

[Jetstream Rider]

Be careful of asking your company. Its is of course good to get info from engineers etc, but in a number of problems I have encountered they have not been useful and following their advice would have been dangerous. The first thing is that they may not understand your problem correctly and it is hard to work out if they do or not, the second is you may be speaking to someone who doesn't understand the myriad of other things you need to deal with such as weather etc. When I asked where they would like us to divert to once, all of the options were well beyond range and despite my insistence they kept telling me to go to the places beyond our reach (we ignored them!).

Contacting company is a good idea, but the decision is yours, or rather the Captains.

I'm not familiar with the 73, so won't comment on the specifics.

[captjns]

It all depends where your car is parked, or which diversionary airport has the best hotel and pub.:ok:

[frogone]

I've thought about this one too. The QRH says nothing about 'Land at the nearest suitable airport' which may lull you into a false sense of security however, if you bumble along at FL370 in the dead of night and loose the 2nd HYD system....then your calling for the 'Manual reversion' checklist....My attitude may be conservative, but always stack the odds in your favour...Get on the ground, let ops worry about the onward flight, engineers about the tech aircraft and handling agents about the pax...You walk away license in hand.

IR

[Northbeach]

Davinchi,

I am not sure you will find one “right” answer. There are always many variables. Why did you loose the hydraulic system? Are you sure it is a leak or simple pump failure or did it come apart in the engine accessory drive and now your engine may be compromised as well. We have had more than one airplane pull up to the ramp with a hole in the cowling because something let loose and the flying crew didn’t know the extent of the problem.
Last winter I had an air turn back after loosing an engine driven hydraulic pump on an engine’s maiden (NG-700) flight. The engine driven pump tore itself apart due to a misplaced restrictor contaminating the entire hydraulic system with shredded/pulverized metal and pump components.
In the NG you have a couple of lights and some gauges that monitor pump output and system quantity –that’s it. It’s hardly exhaustive knowledge of the malfunction. What’s the point of pushing on?
I might handle the scenario differently if I was coming out of some isolated troubled spot in the developing world with relative safety and dependable maintenance some 3 hours away, than I would back in my litigious home country.
The overweight landing is not a bid deal. Go ahead, use your emergency authority and land the jet at the maximum certified takeoff weight, thousands of kilos over landing weight. Touch down lightly with a minimum sink rate use all the available runway and write up the overweight landing in the mechanical record. You have now triggered a required maintenance inspection for the engineering/maintenance crew. As long as you don’t break anything it’s not a major item.
In the sim-forget it. Go someplace safe identify the problem run the appropriate checklist, coordinate with ATC/dispatch/maintenance/flight attendants do whatever the necessary performance calculations and come back and land.
Would you have taken the failed hydraulic system airborne? Now that it has occurred, and you are airborne, what are the advantages of pressing on? From a liability standpoint there are many disadvantages to that course of action should the problem compound itself. As pilots sometimes our collective “get the mission accomplished to the destination” instinct may lead us down a path we should not be on.