Question about starting older Garretts

[Tailwheelman]

I heard recently from a guy who flies a Merlin IIB that the starting technique on some older TPE331's (Dash 1, 3, etc.) involved priming the engine while starting to keep it spooling up at the proper rate. I am sure my terminology is wrong here but having only flown Pratts this is foriegn to me. Could anyone shed some light on how this is done. Sounds interesting.

 

[goodgig]

It has been over 17 years, but you sort of tickle the switch to keep the acceleration going. I forget what is called. I don't think they called it a primer. Maybe start enrichment or something? Anyway, if you wanted to toast the engine , you only had to hold that bad boy down!

 

[Axel]

Yeah, I remember that from a MU-2 I used to fly. I believe "start enrich" is the correct term, but it has been a long time so not sure. "Tickle switch" was the accepted terminology.

During start, one finger on the tickle switch and monitor acceleration. If acceleration began to decrease (not RPM decrease but rate of acceleration decrease) a momentary stab on the switch would help it along. Quick, large rise in ITT (EGT? Like I said: been a long time) so you had to watch it closely.

 

[avbug]

It's not just older Garrets. I had the same requirement on -10's and -11's.

The 48 volt fast start system did wonders for getting easy, cool starts, especially under hot and high conditions.

Garrets aren't the only ones. Certain PT6's need pilot modulation to prevent an overtemp...bringing the condition lever to cut off to allow the temp to drop before the speed decays,and then restoring the fuel flow, at several points during the start. This isn't common for most of the pratts, but on some it is.

 

[MauleSkinner]

I was taught to enrich up to a certain temperature on the 331's (don't remember what it was, though ). I did watch a pilot who forgot to release the enrich switch, and the ITT ran right past BOTH redlines and hit the peg. We didn't use that operator anymore. I've also since heard that they had VERY expensive overhauls on that airplane.

The 731's have an enrich button as well, although I've never had to use it. I think it's primarily for windmilling airstarts, and again, you enrich up to a specific ITT.

Fly safe!

David

 

[avbug]

Generally enrichment on the TFE-731's is a cold weather function, only.

Enrichment can be used on the TPE-331 to enhance acceleration, but with prudence.

 

[waka]

It has been over 17 years, but you sort of tickle the switch to keep the acceleration going. I forget what is called. I don't think they called it a primer. Maybe start enrichment or something? Anyway, if you wanted to toast the engine , you only had to hold that bad boy down!

10 years for me so I am more current than you!

I think it was called SFE, Start Fuel Enrichment. If there is fun to be had while starting a turbine engine, a TPE331 would be the most fun.

Damn! I'm talking about fun and starting an engine in the same sentence......I need to get a life!:0