ARM505 Posted January 17, 2009 Posted January 17, 2009 It seems like airliners, when compared to helicopters, have much larger margins of bleed air available from the engines. Plus, airliners tend to have a whole bunch more altitude to play with compared to helicopters, so there's time to sacrifice some thrust. In theory, a crossbleed start could be done in flight, in some weirdly abnormal situation. Some waffling: Having just done several crossbleed starts (unserviceable APU again) this week, it doesn't take much N1 RPM to get the required 30 PSI or so for the X-bleed start on the 737 - and as far as I remember, doesn't the QRH show envelopes for 'Starter-assist', and 'No Starter assist', ie it doesn't really care what the air source is? I'm going from memory here as I don't have a copy of a QRH with me. Therefore, in theory, you could use crossbleed in flight, although the 'Engine Inflight Start' checklist does pretty much tell you to use the APU, especially since you'd also need it to power the failed engines generator bus as well. All from memory, so I could be a little off on wording of the QRH bits. I have a technical refresher on the -200 coming up as well, so I suppose I should be studying anyway....
IvanK Posted January 18, 2009 Posted January 18, 2009 (edited) Not true Shep. Cross bleed starts airborne are certainly options in B767,B744,A330,A380 :) In these types when outside the Windmill start envelope the ECIAS/ECAM directs the pilot to perform a Cross Bleed start. Mind you in these types there is nearly always surplus Bleed Air to use. Edited January 18, 2009 by IvanK
ericinexile Posted January 18, 2009 Author Posted January 18, 2009 (edited) ...Having just done several crossbleed starts (unserviceable APU again) this week, it doesn't take much N1 RPM to get the required 30 PSI or so for the X-bleed start on the 737 - and as far as I remember, doesn't the QRH show envelopes for 'Starter-assist', and 'No Starter assist', ie it doesn't really care what the air source is? I'm going from memory here as I don't have a copy of a QRH with me. Therefore, in theory, you could use crossbleed in flight, although the 'Engine Inflight Start' checklist does pretty much tell you to use the APU.... APU Bleed Limitation...Max Altitude 17000ft. The APU is there mainly for electrical needs not inflight starts (unless things are really, really bad). But boy have we digressed... AirTito. Thanks for the answer. Kamov is forgiven and I now know that starting an engine inflight is not a big need in the Ka50. What other sim can we have this kind of professional discussion over. Edited January 18, 2009 by ericinexile Smokin' Hole My DCS wish list: Su25, Su30, Mi24, AH1, F/A-18C, Afghanistan ...and frankly, the flight sim world should stop at 1995.
Shepski Posted January 18, 2009 Posted January 18, 2009 (edited) What airline do you fly for Shep? Canadian North Airlines on a 737-200 adv. Our SOP has no mention of an inflight cross bleed start. We would do a windmilling start and if that failed we would continue single engine. The restart envelope is as low as 160 KIAS. Like I said, I can't see a situation where you couldn't descend to a lower altitude and do a windmilling start where by an inflight cross bleed start was required but I guess the newer machines have that option as mentioned above. Edited January 18, 2009 by Shepski
Recommended Posts