Twin Commander
General Category => Engines => Turbine Commander Engines => Topic started by: Steve binnette on February 27, 2020, 01:45:36 pm
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For the last few months I have noticed my right engine was slow to start. At around 40% the acceleration would lag but it would ultimately start.
Then last Thursday we were headed to Cabo San Lucas with my youngest daughter and her friends. This time the engine would not accelerate past 40%. It just stagnated there. I aborted the start and waited a few minutes. I was thinking I might have some weak batteries and an old starter.
So I decided to start the left engine first and do a cross generator start on the right engine. Same problem. The left engine started normally and the right stagnated at 40%.
I had everybody deplane and called for a GPU. It took a little while for the GPU to arrive but once it did I attempted to start the right engine again. It started normally! So we departed for Cabo and had a great flight.
On departure out of Cabo and Brown Field where we clear customs I used a GPU and was able to start the right engine at both stops no problem.
Once on the ground at home in CMA I called Bruce and the guys at Byerly Aviation. Highly recommended, they were extremely helpful.
I was sure I needed a new starter and maybe a set of batteries
They guys at Byerly we’re not so sure. They told me that typically a starter either works or not. My idea of a old draggy starter with weak batteries was my own creation. Some kind of expectation bias, maybe?
They asked me if I had tried a manually start, bypassing the SRL computer. I was embarrassed to say no I had not thought of that but it was a great idea.
When I did the manual start the right engine started fine. The problem was that the SRL was not priming the engine properly during start.
So I get in touch with Byerly and ask when can I get a new SRL computer? They recommended I swap the boxes first to confirm it is the SRL computer.
It seemed silly but the SRLs are very easy to access so we did it. When the cannon plug was pulled out in the right SRL it was dirty so we cleaned both plugs with contact cleaner and reinstalled the plugs.
I pulled out 9812S and fired up both engines. The problem was gone! Both engines started normally!
Couple of lessons for me. Keep an open mind and search out other opinions. I was convinced I needed a new starter, obviously I was wrong.
It was a great outcome.
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Sorry not related to your story Steve, but great pic of you cleaning the bird!
https://sfw.furaffinity.net/view/21596850/?__cf_chl_jschl_tk__=c48bd32022c0673683260f87fdcffd6cac660f5f-1582837077-0-AcL6FhdKrxedw-Q_fcl8Bn6vw1cfa9r5jsvT4EnBg1cVy0hdU66fU3ELCU7RtWblNsN_PzviaG7YJDsFYqWpzXO5yCHf9sPTIElY9h5682tL79YDe3pS9fPJcc1fUP2sC9hjN2-7eHL4nSw4Gjmu90cx5qs-eY2bumq6XOiaKdVwifwhGuQAhSLRr87B7cYFCl4N2FrItLDzdfPPw0gq9GhorU3RuVldws3BLuxLDRvtvnp1NXOZ2Di_whD8oD3gCcnB-mLGnXm7iPZAlEABo39BbWytoy_00rwD5xAB4jeg
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That is a good lesson, and a great outcome. It is amazing what havoc a dirty cannon plug can wreak!
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I think that someone else awhile back had a problem with the cannon plug as well and the cleaning of same resolved their issue also.
I am curious as to why the apu start would be any better with the cannon plug at fault? I almost always use the apu for starts so maybe I should check them as I will not always be able to use the apu.
And great pic by the way
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I would guess the voltage is just slightly higher on GPU starts, and that's enough to break through the bit of corrosion on the cannon plug. That's my theory, anyway.
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Love that photo! Thanks
I think Don is correct the extra amperage did the trick. It confused me too?
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Glad it worked out in the cheapest possible way! Not always the case in aviation... ::)
Are you wiping bugs of leading edge? :D
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No bugs I just always seem to carry a rag on my walk around. Camarillo to Vegas is a low bug environment!
Funny group those airplane spotters. Could be hiding anywhere.
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Paparazzi of General Aviation for sure 8)
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I forgot to ask-- when you were having it hang at 40%, did you try to give it a little extra bump using the start enrich button?
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Don I did not try that. Probably should have. Will the enrich system work with the SRL still on?
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Yes, absolutely. In my younger days, I flew with some guys who used it regularly in the theory that the start would be quicker and the wear on the engine less... I'm not convinced, but whatever!
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Good to know. Thanks
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With normal SRL function, I thought the enrich was engaged as soon as it hit 10% and that was what was not working automatically in Steve’s “situation”? That was the reason I adopted the practice of lighting off the -10T with the little button depressed- because that’s how the big boy’s 511K’s worked, or so I was told by the guru of the largest 331 shop. Better fuel pressure, atomization, acceleration, etc.
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It engages, but the computer modulates it once it gets to a certain point. However, you can press the button to override the computer's judgement and dump more fuel in there if you want to. At least, that's what I remember-- I've never pressed the button in my 980.
From what I recall of the -10T, it has no computer (YOU are the computer!) so you have to press the button as it comes up, and then modulate it yourself.
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It engages, but the computer modulates it once it gets to a certain point. However, you can press the button to override the computer's judgement and dump more fuel in there if you want to. At least, that's what I remember-- I've never pressed the button in my 980.
From what I recall of the -10T, it has no computer (YOU are the computer!) so you have to press the button as it comes up, and then modulate it yourself.
Exactly. The SRL takes it right to target egt and the modulates it thereabouts. At least that’s what it’s supposed to do. You can see the egt needle wiggle in the 980/1000 as it primes. I get great joy watching that all happen automatically but then I’m easily entertained. Enriching the -10T depends more on how the fuel control setup, OAT, oil temp and all of that. But the goal should be to modulate it around the target EGT. But lighting it off with the enrich depressed always seems to make it start better. But we digress ...
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I love showing off the auto start function. People ask if it has a fadec!
What other airplane back then had an autostart where you sit on your hands and just watch the lights go on and off and the the needles climb and settle?
Pure black box magic. Love it