Air Ambulance BE20 (KLNK)

[jafo20]

It could be that there was an overtemp in another phase of flight that people just blamed on a hot start.

 

[jafo20]

Avbug, are you saying you should be jockeying the condition levers around if you can't get the starter to spool up enough?

 

[avbug]

Some engines tend to start hot and slow. The -45R I mentioned is one of them. Pilot modulated starts are not an abborant start proceedure...it's SOP on some aircraft and systems.

If you're getting a slow start and it's trying to climb, using the fuel cutoff to modulate the start and milk it up is far better than either being stuck somewhere, or letting it start hot. It's a legitimate pilot technique, and a necessary one on some engines.

Pilots who are used to plug and play self limiting engines find this unusual, but it's not. It's just that you probably haven't come across it before.

 

[pilotman121]

Jockeying the condition levers!

There is usually a bigger problem, if you have to resort to those kind of measures and it would not be approved by Pratt & Whitney.

 

[jafo20]

I've heard of adjusting throttles when you're stuck around, like 40% or so, with a hung start. I guess I'm unclear on whether you're saying it should be done below, say, 10% or not.

 

[avbug]

No, if you can't get ten percent off the battery, then a battery start shouldn't even be attempted. Any Pt6A ought to do about eighteen to twenty percent on the starter with battery only, before fuel.

Some engines go warm at lower RPM's, say 30, 35, 40, etc. Going to cutoff while the temp drops and RPM doesn't appreciably droop allows one to put in the fuel again, continue with the start, without over temping. It's a pilot modulated start. Some powerplants are throw-the-switch-and-forget, but some aren't. In either case, if the temp is climbing and RPM isn't, before calling a hung start (in which everything should stop, temp included), consider a pilot modulated start to protect from overtemp.

This isn't the same as bumping the power lever during the start. I'm talking about preventing a hot by going to cutofff, the right back to on again. It's sometimes referred to as "blipping." It's either that, or go to cutoff and stay there and let the engine motor. However, if one wishes to continue the start, which may well be preferable, it's a matter of the pilot protecting from over temp. If the engine does overtemp, it's operator error, not the fault of the engine.

 

[jafo20]

Okay, I think I understand you now. I thought blipping below 20% would totally burn the engine up, but you're not talking about that. You're also not talking about getting your secondary nozzles to kick in with a hung start. You're talking purely about temp control.

Does indicator lag in the ITT gages factor into this? Even with thermocouples, it takes a second for the needles to move. Do you target a reduced temp on the ITTs to prevent momentarily overtemping things and shocking your hot sections? Do you depend on the 2 second, momentary ITT limitations?

How does the battery factor into this?

Usually, with an overtemp on the start, we just discontinue the start, clear the engine and try it again. Usually I can get one engine and generator online, so battery power to get the bad engine up isn't an issue. Trying to do a pilot modulated start, as you describe, is something I'd probably foul up. I could see myself waiting a second too long to reapply the fuel and really burning the engine up. Thankfully, my AFM saves my ego with a little limitation that says:

"If starting attempt is discontinued, the entire starting sequence must be repeated after allowing the engine to come to a complete stop."

Just to clarify, when you mentioned blipping the engine with low battery power, you were talking about only having enough batt. to get one solid start out of the engine but not enough to make a second attempt. Is that correct?

Finally:

All of us who post on this site, myself included, think we have something important to say. Combine that typical pilot egos and we get a little touchy when people questions us or suggest something we haven't heard of. We see something that initially strikes us as silly, when, in reality there may be some merit to someone's statement. We also see things that seem reasonable that may be foolish. When I ask these questions, I'm not trying to fight you, or make you look silly. I'm simply curious about a technique which I haven't observed, and perhaps it'll help me get an engine started on a lousy, frigid night.

 

[G-force]

Be-200 @ Lnk

Has this aircraft been sold Yet????????

 

[pilotman121]

G-force

They cannot find anyone willing to buy the aircraft,it is in bad shape and needs some good maintenance.

 

[onthebeach]

This is what I was referring to by increased ITT limits between the -41 and -42.

[FONT=verdana, arial, helvetica]PT6A-41[/FONT][FONT=verdana, arial, helvetica]850[/FONT][FONT=verdana, arial, helvetica]403[/FONT][FONT=verdana, arial, helvetica]The PT6A-41 is an engine model which features a modified compressor and 2-stage power turbine for higher ratings. [/FONT][FONT=verdana, arial, helvetica]PT6A-41AG[/FONT][FONT=verdana, arial, helvetica]850[/FONT][FONT=verdana, arial, helvetica]403[/FONT][FONT=verdana, arial, helvetica]The agricultural version of the PT6A-41. [/FONT][FONT=verdana, arial, helvetica]PT6A-42[/FONT][FONT=verdana, arial, helvetica]850[/FONT][FONT=verdana, arial, helvetica]403[/FONT][FONT=verdana, arial, helvetica]Similar to the PT6A-41 except for increased cruise rating and increased ITT limits with improved compressor reduced loss exhaust ducts. [/FONT]