Message-ID: <3881E564.E1205F2B@regandesigns.com>
Date: Sun, 16 Jan 2000 07:36:04 -0800
From: Brent Regan <brent@regandesigns.com>
To: Lancair List <lancair.list@olsusa.com>
Subject: Re: AIM Carbon Monoxide Detector
Mime-Version: 1.0

          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
          <<  Lancair Builders' Mail List  >>
          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> 
>>
Regarding David's comments about high CO concentrations in his airplane, he
mentioned a couple of things that may lead to a source. Here is what we
know:

Dave's plane is not pressurized.
Dave was doing 2G turns just before reading the CO meter.
I have seen dramatic CHT changes at high power settings during turns
indicating disrupted airflow.
I regularly have to clean engine oil out of the gear wells.

Here is my theory: At high lift coefficients/ AOA, engine exhaust is
entering the cabin via the gear wells.

The Test: Fly in normal cruise and note the CO then do a series of high bank
turns, see if the CO changes.

BTW, not being pressurized also explains why the bleed air heater is
ineffective. In a word, dilution. You only get about 50 CFM out of the sonic
venturi, not enough in an unpressurized pane to overcome several hundred CFM
of flow from the baggage area. It is ironic that an airplane with better
ventilation may be more susceptible to CO than one with less.

FYI. I believe that Mike Dehate Jr. the airplane builder is Mike Dehate's
(the test pilot) son.

Regards
Brent


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
LML website:   http://www.olsusa.com/Users/Mkaye/maillist.html
Builders' Bookstore:   http://www.buildersbooks.com/lancair

Please send your photos and drawings to marvkaye@olsusa.com.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>