Steve,

The wideband may be picking up a small fuel imbalance between the two rotors. Or is could be perfectly normal for all = widebands to jump around. I would expect an increase in EGT’s with a gradual = partial blockage. A high EGT alarm would give some indication. I would = also expect a steady but higher than normal temp with a build in restruction. = But with a sudden blockage at high power? The answer may not be of any value = since only a pressure sensor would tell the pilot to stop trouble shooting. =

Bobby

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Steven W. Boese
Sent: Sunday, March 20, = 2011 8:20 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = Forced Landing.

Bobby,

I have not done any testing with a wideband O2 sensor. Unless the engine were operating right on a = threshold of a large untuned injector pulse width change (staging is the only = thing that comes to mind), it seems unlikely that the variation in O2 sensor would = be associated with injector delay.

Within the limits that were = tested, the EGT increased with increased exhaust back pressure due to partial blockage. The mixture was somewhat rich and no change in O2 sensor = was seen. Lean mixtures were not investigated at that = time.

Steve

<= /o:p>

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bobby J. = Hughes
Sent: Sunday, March 20, = 2011 7:46 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = Forced Landing.

Steve,

Thanks for the offer. Actually I = think it would be great if you could conduct a test. I had thought about a block = off plate that could be pulled into place with a long wire. This would = allow a high power test run with a sudden blockage. It’s the only way I = can come up with to create a not so dramatic reinactment. Your test stand = would be a better platform then the airplane. The engine was popping and shaking = when the failure occurred. As best I can remember my wideband O2 was off the = scale lean but I’m not certain. Speaking of wideband O2’s. My = wideband has always jumping around a few 10ths or more. My EM3 get’s a = narrowband output from the wideband. The EM3’s mixture bar appears stable. = Could the wideband be seeing a injector bounce associated with the injector delay? = As an example when leaned for cruise, say 13.2 it’s often switching = rapidally between 13.1 and 13.3. At this point the engine seems reasonable smooth. = The larger the bounce the less smooth the engine becomes. Have you done any = of your testing with a wideband?

Bobby

<= /p>