larry(at)macsmachine.com
Guest
|
 Posted: Tue Mar 07, 2006 5:50 pm Post subject: EGTs high on descent? |
 |
|
*Hi guys,*
*It was suggested that the following should be put into Zenith pages because a 912 Rotax with
Bings might just provide a similar experience to one I recently had with my Stratus.*
*I was flying yesterday and noticed something interesting for those of us with Bing carbs.
EGTs had climbed to their normal 1420 at high climb 4800 rpm and the higher I got (4500 ft),
the more the EGTs drifted lower. It eventually permitted a high rpm without going above the 1400 deg f.
Nice for a good cross-country cruise, but as I descended to land, EGTs climbed back up to set-limits on
my EIS and rpms had to be reduced to keep EGTs at or below limits. Not something I worried about, but
it seemed strange to see EGTs going the wrong way while descending. On final everything was well below
limits, but I was wondering about the altitude compensating carbs and if they ever get out of whack or
is this normal. I posted an inquiry for others experiences.*
*Don Walker wrote:*
*I dunno, just brainstorming with you. Looks like increased speed would increase cowl pressure to affect
the mixture...and vice versa. Rate of descent may have something to do with it, too. I assume you are
letting down at three to five hundred fpm? I am glad you are noting these things, Larry, Helps us all. Don*
*Don,
I spoke with technical support person at Bing and he said that on
descent, sometimes cowl pressure under lowering throttle settings
are still enough to lean out the mixture a bit and temps will go up.
You were right. He also said that the enrichment (choke) cable could
be pulled during the descent while rpms are reduced from 4500 rpm to 3500 rpm
and the EGTs should return to normal. I'd have to try that on the next flight out.*
*Hi guys,*
*I called the Bing folks and was advised that rising EGTs during descent could be countered
by using a little choke enrichment. Yesterdays flight proved that as we descended from 4000 feet at
500 fpm to 2500 ft. EGTs hit the set-point of 1450-degrees, and the warning light flashed, so I pulled
just a little (choke) enrichment and the EGTs dropped to 1390-degrees F rather quickly and stayed under
1400-degrees the rest of the way. We had a 42-degree ambient temp and the rest of the temps were in the green.
Anyway, it worked.*
*Fly safe,*
*Larry McFarland - 601HDS - Stratus at 85 hours - at www.macsmachine.com*
| | - The Matronics Zenith-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Zenith-List |
|
|
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
