LMML 14/32 From Malta, joined Jan 2001, 2565 posts, RR: 6 Posted (8 years 4 months 1 week 6 days 18 hours ago) and read 2404 times:
Yesterday, we had to return to base after the number 2 generator failed and the APU quit minutes after it was started at FL340. How serious is such a situation? What did the B733 lose in this case? Would the APU and the number 1 generator have sustained normal flight for 3 hours? If so what are the flight limitations?
MD11Engineer From Germany, joined Oct 2003, 13605 posts, RR: 63 Reply 2, posted (8 years 4 months 1 week 6 days 14 hours ago) and read 2354 times:
While one generator can power the plane's systems (minus the cabin bus with the high power consumption galleys) through the transfer busses, there would have been virtually no redundancy left. The only redundancy in case of the last generator packing up would have been the ship's battery, which can provide emergency power to the standby instruments for about 20 minutes.
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 69 Reply 4, posted (8 years 4 months 1 week 6 days 14 hours ago) and read 2349 times:
Had to disconnect a generator drive once on a 737. Started the APU first, then turned off the bad generator and disconnected it. That happened over New York State and we flew all the way to the west coast on two gens. Not a problem at all except that we had lost our redundancy. Had the APU quit at some point we'd have had a whole new situation.
Turned out the CSD was just low on oil. Temperature was high, rise was high and when the frequency started to fluctuate it was time to cage it.
Happiness is not seeing another trite Ste. Maarten photo all week long.
CdfMxTech From United States of America, joined Jul 2000, 1338 posts, RR: 28 Reply 5, posted (8 years 4 months 1 week 6 days ago) and read 2213 times:
The 737 Classics would lose everything on the opposite side Generator Bus, which in turn powers the main Bus.
In this case, the No.2 side Gen & Main Busses would have been unpowered.
Here is what you lose:
No. 2 Tank Forward Fuel Pump
Center Tank Left Fuel Pump
Fuel Temperature Indicator
Generator Bus No. 2
TR Unit No. 3
Equipment Cooling - Alternate If Switch is to Alternate
Left Side Window Heat
Right Forward Window Heat
Right No. 4 & No. 5 Window Heat
Right Elevator Pitot Heat
Temp Probe Heat
RIGHT OUTBOARD LANDING Light
LEFT INBOARD LANDING Light
RIGHT RUNWAY TURN Light
Engine Vibration Amplifier
MD11Engineer From Germany, joined Oct 2003, 13605 posts, RR: 63 Reply 7, posted (8 years 4 months 1 week 5 days 17 hours ago) and read 2161 times:
What do you think you have the two bus tie breakers for (BTB1 and BTB2)?
They can close them and connect the left transfer bus to the right transfer bus. 90kW of power are quite enough, especially since the galley busses will be automatically shed, leaving all power for the aircraft systems. This will mean no light in the cabin, no galley power (except for the emergency lights) and no working toilets, but you can live without it. The plane was designed that, while normally each generator would feed it's own half of the plane (therefore eliminating the problems going with synchronising AC generators), in necessary each generator ca power the whole plane. E.g. the APU generator is doing exactly this on the ground and it is not bigger than the engine generators.
One generator is enough to power the systems, you just don't have ANY redundancy left. Should the last generator pack in, then you'll be down to the battery, dark cockpit and standby instruments for 20-30 minutes.
MD11Engineer From Germany, joined Oct 2003, 13605 posts, RR: 63 Reply 9, posted (8 years 4 months 1 week 5 days 7 hours ago) and read 2058 times:
45 kW should still be able to power the whole aircraft, without the high current consumers galley ovens and coffee makers. If necessary you might have shut down one of the electric hydraulic pumps temporarely (during cruise, switch it on during approach again). The whole 737 electric system has been designed to have some redundancy.
Even then, with 2/3 of my generating capacity off, as a pilot, I would be looking for the next airport for an emergency landing.
Buzz From United States of America, joined Nov 1999, 697 posts, RR: 23 Reply 10, posted (8 years 4 months 1 week 2 days 16 hours ago) and read 1899 times:
Hi LMML 14/32, Buzz here. MD11 Engineer pointed out that you can get along and fly with a single generator.
But many pilots get to thinking... what's the next bad thing that will happen to me? So if you lose that last generator you really have to work to find an airport (night? fog? rain and wind?) and get that sick airplane on a runway. It's not quite like flying a Cub or a Champ with the windows open on a nice day.
MD11Engineer From Germany, joined Oct 2003, 13605 posts, RR: 63 Reply 11, posted (8 years 4 months 1 week 2 days 16 hours ago) and read 1893 times:
Obviously, when you are down to one generator, you should start looking for the next available airport. You are not yet in a direct emergency situation, but you have lost all redundancy, so, if the last generator packs in, you will be up sh*t creek without a paddle.
LMML 14/32 From Malta, joined Jan 2001, 2565 posts, RR: 6 Reply 12, posted (8 years 4 months 1 week 2 days 11 hours ago) and read 1851 times:
Thank you all for your replies. Put your mind at rest. We returned to base and were on the ground in 20 minutes. The generator was replaced and we were on our way again in no time - minus 4 passengers who decided that one scare was enough for one day.
Bjones From United States of America, joined Feb 2002, 123 posts, RR: 0 Reply 14, posted (8 years 4 months 1 week 1 day 23 hours ago) and read 1802 times:
The 737 can be operated with either one engine generator inop or the APU (or APU generator) inop. In either case as long as it is properly MELd then you can operate a revenue flight. With one engine driven generator inop there is a fuel burn penalty because you must fly with the APU running.