3505786-1 air turbine starter

[edwardlcy]

Hi guys, just curious for knowledge sake, for 3505786-1 air turbine starter, when inflight suddenly start valve light illuminate and start valve open, will the air turbine starter crank and get damaged? Thanks.

[Ronc]

edwardlcy,

Never seen it myself but that's the theory as to why they put the light in; previous C-130's had no start valve open lights.

[NATOPS1]

Yes,

The main problem is the very small amount of lubrication inside the starter. after a few minutes the starter will fail and will most likely come apart and damage the engine, cut hoses and electrical wires. Of the two that I know of each time resulted in a FIRE light.

[edwardlcy]

Yes,

The main problem is the very small amount of lubrication inside the starter. after a few minutes the starter will fail and will most likely come apart and damage the engine, cut hoses and electrical wires. Of the two that I know of each time resulted in a FIRE light.

3505786-1 is the part no. for a newer model air turbine starter, older model starter only engages onto the engine when start valve is open and there's bleed air going into the starter, hence damage will occur when start valve is opened in flight and the starter is engaged onto the engine at rpm that is above the limit. is there any new fail safe built into the newer model to prevent this scenario that is not available on the older model?

[NATOPS1]

3505786-1 is the part no. for a newer model air turbine starter, older model starter only engages onto the engine when start valve is open and there's bleed air going into the starter, hence damage will occur when start valve is opened in flight and the starter is engaged onto the engine at rpm that is above the limit. is there any new fail safe built into the newer model to prevent this scenario that is not available on the older model?

No there is no safe guard in place.

If the start valve is “open†and air is going to the starter the starter will try and engage no matter which part you have installed.

The air turbine drive will try to engage and mesh with the rotating gear attached to the gearbox. If it does not mesh the starter will accelerate to maximum rpm then disintegrate after a minute of two; maybe more maybe less.

[Abid kamal]

Hi dears,let me clear your concept,although its too late,

Old or new model

Both have a clutch mechanism, I.e jaw pawls and hub with its drive shaft assy,drive shaft will disengage form starter when starter drive shaft rpm reaches to 8000 to 10000,

During flight engine rpm alway above 13000 , due to high rpm,starter drive shaft will remain disengaged,due drive shaft pawls flung out,weather air pressure going to starter turbine or not.

I hope you understand my broken English.

[NATOPS1]

1 hour ago, Abid kamal said:

Hi dears,let me clear your concept,although its too late,

Old or new model

Both have a clutch mechanism, I.e jaw pawls and hub with its drive shaft assy,drive shaft will disengage form starter when starter drive shaft rpm reaches to 8000 to 10000,

During flight engine rpm alway above 13000 , due to high rpm,starter drive shaft will remain disengaged,due drive shaft pawls flung out,weather air pressure going to starter turbine or not.

I hope you understand my broken English.

I agree it should not actually be able to engage but the fact it will be "disengaged" does not mean it will not try to engage as it spins up nor that it will spin up to max rotation speed "unladen" and disintegrate causing damage to the engine.