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Has anyone heard of the Turbo sr22 Cirrus having this sort of problem. It does not have the exhaust interconnect that the typical tsio-550 has. It has instead, two wastegates. There is a cable connecting one to the other and the one controller moves them both this way.
Lynn, does your exhaust have an interconnect or does it have two wastegates like the Cirrus?
Matt
From: Gary Casey <casey.gary@yahoo.com>
To: lml@lancaironline.net
Sent: Fri, September 10, 2010 12:18:12 PM
Subject: [LML] Re: Engine failure ATC Transcript Super Legacy Twin Turbo TSIO 580
The questions below are certainly correct. Another post said that the two turbos were plumbed to be independent from each other, each with its own wastegate. Then how was the fuel metered? One could use a separate fuel control servo on each turbo, but I doubt that it was done that way. I suspect a single servo fed both turbos, measuring the total air. That's the difference between the Continental proprietary system and the Lycoming system built by Precision Airmotive(was Bendix). The Bendix system measures air flow and the Continental system measures throttle position and engine speed, with altitude compensated versions being compensated for manifold
pressure. Regardless, having one bank pressurized to a different pressure than the other makes accurate fuel metering difficult or impossible. If indeed one bank lost boost it would be very unlikely that the engine could be made to run on more than 3 cylinders at a time (and I also suspect that the report of "3,4,6" was incorrect - it mostly likely was 2,4,6 or 1,3,5. Or it would not be unlikely that the temp probes were mixed up and never detected.
When I changed any part of the design I used the rigor of conventional Failure Modes and Effects Analysis (FMEA) to evaluate all possible failure modes. That would have driven me (I hope) to provide an intake manifold interconnect between engine banks. I like single turbos, partly for that reason.
Gary Casey
ES, not P, not even T
notwithstanding Charlies' comments I don't understand exactly what happened to 3,4,6. The video says Mark tried moving the mixture both directions with no success. I'm not understanding why that didn't help...unless half the cylinders have reduced pressure and other half have higher pressure so there is not optimal mixture. Also why 3,4,6 and not 2,4,6. Was this a Lycoming? also, also, why did the plugs foul so quickly?
on a Continental the turbo outputs are merged so that if you lose, e.g. one hose, you would lose pressure on all cylinders. at least then all cylinders face the same mixture situation.
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