View Full Version : 737-300 fuel/suction feeding
cheapfuel
15th Apr 2003, 11:00
737-300---With the fuel crossfeed valve in the open position,it is possible to feed both engines from one tank utilizing that tanks fuel pumps. My question is in reguard to suction feeding. Can one fuel tank suction feed both engines? And while were discussing fuel suction, how is the airplane able to suction feed the APU, when it appears that the wing tank is lower than the APU?--thanks alot
Sonny Hammond
15th Apr 2003, 13:32
One tanks pumps can feed both engines thru the xfeed, thats how fuel balancing is done. (I think that is what you're looking for)
As for the apu, the pump on the apu sucks the fuel, but we leave one left main tank pump on normally to increase the life of the APU( thats what we are told but i suspect it increases the life of the apu edp.:ok:
cheapfuel
15th Apr 2003, 22:42
Thank you Sonny--APU question is satisfied.--What I was getting at relating to one tank suction feeding both engines was : Will both engines be capable of continuous operation receiving fuel from one tank(suction feeding),with all pumps off. Since my original post, I have gone back, looked at the flow chart, and have concluded:"With all pumps off, crossfeed open, both tanks will probably balance out". It is now apparent that there is no outlet valve to isolate a single tank. Does this sound correct??. thanks ahead of any reply---
The engines can suction feed from the MAIN tanks only up to 30,000 feet. You always want a fuel pump on in any situation.
Sonny Hammond
16th Apr 2003, 01:48
RTFQ...I never learn!:(
Can't answer that, but i reckon to find out, your either in the sim or having a bad day out.....
eng1170
17th Apr 2003, 08:05
Before putting the kite in the hangar we do a check of the boost pump bypass valves on a ground run. This involves both engines started, all pumps then turned off, monitor EGT, n1,n2 and FUEL FLOW, steadily wind her up to static t/o power whilst ensuring no popping/banging/coughing etc and ensuring the fuel flow is steady and equal for both engines. Left at static t/o for a couple of mins to monitor fuel consumption and if all is satis, throttle back and monitor fuel flows and watch out for signs of a flame-out.
I've done loads of these and have never seen an aircraft where the engines struggle to get fuel or flame out.