Starter engagement during engine relight

[tom775257]

Hello all,

(With basic reference to Airbus 320/1)
Basically if you are trying to relight a jet engine that has flamed out using starter assist, it seems to me that there is a strong possibility of the N2 windmilling being above the (usual) max N2% for starter engagement.

Is this a limit that is designed for longevity of the starter coupling and therefore can be ignored? I see no reference to max N2 in starter assisted relight in the QRH, however in the limitations for the engine there is a maximum of 18%N2 with the IAE V2500, and 20% on the CFM56.

Cheers

[FE Hoppy]

I'm not Ab rated but is there a re-start envelope divided by airspeed and altitude? There may be a windmill only area for high speed and altitude. Generally as the rotor (spool) is offloaded due to the windmilling of the engine and the low pressure, crash re-engagements aren't considered a problem within the bounds of the airstart envelope.

[deltahotel]

Can only speak for the 757. The windmill start envelope (speed bands at different heights) is shown on upper EICAS. If assisted start available, it will show as X Bld on lower EICAS above the N3 guage - usually need to slow to about 250 ish to get this showing.

DH

[Old Fella]

On the RB211 powered B747 Classic the QRH clearly indicates Air Starts at below 250 KIAS will require Starter Assistance. As an indication of what windmilling RPM's you should get on the RB-211 @ FL200 $ 250 KIAS. N1 22% - N2 9% and N3 13%. For a normal Ground Start the Start Lever is moved to Rich at 15% N3 and Starter Cut-out is at 50% N3. Windmilling RPM should not cause a problem for engaging the Starter.