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#11
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Engine problem - Seneca II
"BDS" wrote in message
I wonder if the bearings could be changed out as opposed to replacing the entire turbo. Yes, along with the seals. However, when you pull the compressor off the shaft to slide the bearings off, you disturb the balance. Balance is critical at 130k rpm. Then there is that pesky FAA thing about engine accessories having to be overhauled at a repair facility. Do you use Marvel Mystery Oil? D. |
#12
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Engine problem - Seneca II
"Darkwing" wrote in message So what happens on a turbo
plane if you pull the power back real fast without a wastegate? On a car if the wastegate fails you can damage the engine. The cylinders shock cool and crack with a strong pssibility of the heads seperating from the barrels and/or seizure from the barrels shrinking around the pistons. I have had the distinct pleasure of driving a Lingenfelter Twin Turbo 01' vette on more than one occasion, 650hp, 6 speed, BAD BAD BAD!!! Sweeetttt!!!! D. |
#13
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Engine problem - Seneca II
"Scott Skylane" wrote in message That's correct, but it *does* have
pop-off boost valves. So... I can firewall the throttle levers without overboosting the engines on a Seneca 2? D. (stock- as in from the factory) |
#14
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Engine problem - Seneca II
Capt.Doug wrote:
"Scott Skylane" wrote in message That's correct, but it *does* have pop-off boost valves. So... I can firewall the throttle levers without overboosting the engines on a Seneca 2? D. (stock- as in from the factory) Doug, Doing so would exceed max rated M.P. by about 1". The Pop-offs are designed to be last chance protection against overboost, and are not to be relied upon in normal operation. See: http://www.kellyaerospace.com/articl...bocharging.pdf Look at the section titled "How do you spell relief" on page 8. Happy Flying! Scott Skylane |
#15
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Engine problem - Seneca II
"Scott Skylane" wrote in message
Doing so would exceed max rated M.P. by about 1". The Pop-offs are designed to be last chance protection against overboost, and are not to be relied upon in normal operation. See: I remember 2 little lights in the upper middle of the instrument panel that illuminate when overboosting. Are they activated by the PRV? D. |
#16
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Engine problem - Seneca II
Capt.Doug wrote:
I remember 2 little lights in the upper middle of the instrument panel that illuminate when overboosting. Are they activated by the PRV? D. No, the P.R.V.'s (Pop-Offs) are purely mechanical in nature. They have no electrical function. Happy Flying! Scott Skylane |
#17
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Engine problem - Seneca II
"Capt.Doug" wrote in message ... "BDS" wrote in message I wonder if the bearings could be changed out as opposed to replacing the entire turbo. Yes, along with the seals. However, when you pull the compressor off the shaft to slide the bearings off, you disturb the balance. Balance is critical at 130k rpm. Then there is that pesky FAA thing about engine accessories having to be overhauled at a repair facility. Do you use Marvel Mystery Oil? Not in this aircraft as of yet but I have used it in other non-turboed acft in the past. Can it handle the heat of the turbo and do you think it might help clean the bearings? BDS |
#18
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Engine problem - Seneca II
"Scott Skylane" wrote in message ... So... I can firewall the throttle levers without overboosting the engines on a Seneca 2? Doing so would exceed max rated M.P. by about 1". The Pop-offs are designed to be last chance protection against overboost, and are not to be relied upon in normal operation. See: http://www.kellyaerospace.com/articl...bocharging.pdf Look at the section titled "How do you spell relief" on page 8. I think our overboost lights come on at just over 40 inches. I am pretty sure you can go up to 42 for short periods, but I haven't tried. The throttles on a stock Seneca II are quite sensitive - at sea level ours will reach 40 in mp at about 75% of throw and you can get +/- 2 in by just breathing on the throttles. Most of the time with the load and the runway available I do not need to use more than 35 in so I don't even approach max boost. |
#19
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Engine problem - Seneca II
"Kingfish" wrote in message oups.com... There were a few good suggestions from others already - Turbo bearing coking does make sense, but you clearly know to let the turbo unspool before shutdown so that might not be as likely. (IIRC there is a way to clean up the turbo bearings without turbo removal if that's what it turns out to be) My guess would be the fuel control unit gone wonky; the fact that power returns after richening the mixture might back up that theory, but what are the chances of both acting up simultaneously? Maybe the alternate air diverter is partially open? Out of curiousity, what CHTs are you seeing at 1425 EGT? I know the fuel controls were double checked and adjusted when the problem first came up. That doesn't mean they aren't the culprit, but they seem to act normally when tested. CHTs never get out of the green arc and typically remain at about 75% of the scale. BDS |
#20
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Engine problem - Seneca II
"BDS" wrote in message
Not in this aircraft as of yet but I have used it in other non-turboed acft in the past. Can it handle the heat of the turbo and do you think it might help clean the bearings? Don't know about turbocharged engines. I used it religiously in supercharged R-985s, but that was to prevent sticking valves. D. |
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