 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
mark.bitterlich(at)navy.m
Guest
|
 Posted: Fri Sep 08, 2017 8:31 am Post subject: [Non-DoD Source] Low Pass Engine Sputter |
 |
|
Questions:
Was the low pass out of a dive? I.E. Were you at a much higher speed?
Were you so low as to be in ground effect, again, increasing speed?
Did you happen to look at fuel pressure?
What was the engine RPM set to?
What was the throttle setting? Full forward?
Are your mag drops normal?
Is idle RPM as it always has been? Any change recently?
Has anything been adjusted recently? Timing, any kind of inspections, any hands on the engine?
How long was this "sputter"? 1 second? More than that?
Are you running 100LL ?? Any mixture with car gas? Any additives?
Where were the shutters? Open or closed?
What was cylinder head temp?
Were the fuel tanks full at the beginning of each flight?
Have you verified that fuel tank venting is A-OK?
Obviously with the given information, the best most anyone can do is to make guesses. That said, you need to be ready to switch from one mag to the other if this happens again. Switch to position 1 and then to 2, and see if it clears. I am personally at a loss to understand the relationship to the "low pass", unless you are in ground effect and the aircraft is bouncing around with turbulence at like 20 feet or less off the ground.
In the meantime, I going to risk this advice for fear of reprisal. My Yak-50 has about 32 gallons of fuel total. I have a habit of putting in a full QUART of MMO (Marvel Mystery Oil) per 30 gallons. This is much more than the advised mixture of course. I also USED TO suffer from leading of the valves, and since I began doing this, the problem has completely been resolved. Regardless, you really have to try very hard to put too much of this stuff in the fuel to cause a problem. One quart is a lot, but it does not cause any engine issues at all, and it tends to clean out everything (IMHO). I'd add a quart to your fuel for the next few fill ups, just for GP (General Purposes). But this of course is a WAG.
Obviously the big question here is: Is it fuel, or is it ignition? Typically this kind of thing is ignition related, but it is very hard to bet money on that.
Mark
--
| | - The Matronics Yak-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?Yak-List |
|
|
|
| Back to top |
|
 |
dsavarese0812(at)bellsout
Guest
|
| Posted: Fri Sep 08, 2017 9:25 am Post subject: [Non-DoD Source] Low Pass Engine Sputter |
|
|
All excellent points by Mark and Ernie. M14 or Huosai engine? I'd like
to add; What was the outside air temp and the relative humidityeach time
it occurred? I personally experienced the exact same symptom in a Yak 52
doing the exact same thing and ultimately concluded it had to be carb ice.
Although the carburetor is a pressure carburetor, the IS a very small
window where carb ice can and will occur. So please do not discount
carb ice as causing the problem.
You may want to do the same test twice; once without carb heat and see
if you get the same symptom. If you do, perform the same maneuver only
this time with carb heat.
https://www.aopa.org/-/media/images/legacy/aopa/home/pilot-resources/safety-,-a-,-proficiency/accident-analysis/accident-statistics/epilot-reports/epilot-asf-accident-reports-carburetor-what/nyc02fa025_1.jpg?la=en
Dennis
A. Dennis Savarese
334-546-8182 (mobile)
www.yak-52.com
Skype - Yakguy1
On 9/8/2017 12:30 PM, Bitterlich, Mark G CIV NAVAIR, WD wrote:
[quote]
Questions:
Was the low pass out of a dive? I.E. Were you at a much higher speed?
Were you so low as to be in ground effect, again, increasing speed?
Did you happen to look at fuel pressure?
What was the engine RPM set to?
What was the throttle setting? Full forward?
Are your mag drops normal?
Is idle RPM as it always has been? Any change recently?
Has anything been adjusted recently? Timing, any kind of inspections, any hands on the engine?
How long was this "sputter"? 1 second? More than that?
Are you running 100LL ?? Any mixture with car gas? Any additives?
Where were the shutters? Open or closed?
What was cylinder head temp?
Were the fuel tanks full at the beginning of each flight?
Have you verified that fuel tank venting is A-OK?
Obviously with the given information, the best most anyone can do is to make guesses. That said, you need to be ready to switch from one mag to the other if this happens again. Switch to position 1 and then to 2, and see if it clears. I am personally at a loss to understand the relationship to the "low pass", unless you are in ground effect and the aircraft is bouncing around with turbulence at like 20 feet or less off the ground.
In the meantime, I going to risk this advice for fear of reprisal. My Yak-50 has about 32 gallons of fuel total. I have a habit of putting in a full QUART of MMO (Marvel Mystery Oil) per 30 gallons. This is much more than the advised mixture of course. I also USED TO suffer from leading of the valves, and since I began doing this, the problem has completely been resolved. Regardless, you really have to try very hard to put too much of this stuff in the fuel to cause a problem. One quart is a lot, but it does not cause any engine issues at all, and it tends to clean out everything (IMHO). I'd add a quart to your fuel for the next few fill ups, just for GP (General Purposes). But this of course is a WAG.
Obviously the big question here is: Is it fuel, or is it ignition? Typically this kind of thing is ignition related, but it is very hard to bet money on that.
Mark
--
| | - The Matronics Yak-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?Yak-List |
|
|
|
| Back to top |
|
|
nigel.willson(at)yakdispl
Guest
|
| Posted: Fri Sep 08, 2017 9:28 am Post subject: [Non-DoD Source] Low Pass Engine Sputter |
|
|
What are you doing with the throttle is probably a pertinent question....
Closing while diving and then opening during the pass perhaps?
Technically, you should just leave it at aerobatic power all the while....
Apart from the fact that if you were in the UK (not sure about FAA rules),
you'd be pulled up anyway for doing low passes without an exemption from the
Rules of the Air since this type of approach can hardly be called an
approach to land.....
Regards,
Nigel Willson
Flying Instructor & Examiner | Airshow Organiser | Display Pilot
Mobile:
+44 (0)7809 116676
Email:
nigel.willson(at)yakdisplay.com
Web:
http://easyppl.com
http://greatbritishairshows.com
http://yakdisplay.com
--
| | - The Matronics Yak-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?Yak-List |
|
|
|
| Back to top |
|
|
dsavarese0812(at)bellsout
Guest
|
| Posted: Fri Sep 08, 2017 9:35 am Post subject: [Non-DoD Source] Low Pass Engine Sputter |
|
|
How about a "practice missed approach"?
A. Dennis Savarese
334-546-8182 (mobile)
www.yak-52.com
Skype - Yakguy1
On 9/8/2017 1:26 PM, Nigel Willson wrote:
[quote]
What are you doing with the throttle is probably a pertinent question....
Closing while diving and then opening during the pass perhaps?
Technically, you should just leave it at aerobatic power all the while....
Apart from the fact that if you were in the UK (not sure about FAA rules),
you'd be pulled up anyway for doing low passes without an exemption from the
Rules of the Air since this type of approach can hardly be called an
approach to land.....
Regards,
Nigel Willson
Flying Instructor & Examiner | Airshow Organiser | Display Pilot
Mobile:
+44 (0)7809 116676
Email:
nigel.willson(at)yakdisplay.com
Web:
http://easyppl.com
http://greatbritishairshows.com
http://yakdisplay.com
--
| | - The Matronics Yak-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?Yak-List |
|
|
|
| Back to top |
|
|
nigel.willson(at)yakdispl
Guest
|
| Posted: Fri Sep 08, 2017 9:47 am Post subject: [Non-DoD Source] Low Pass Engine Sputter |
|
|
Still has to be done in the landing configuration if you're coming that
low...... otherwise, a practice missed approach that starts with the gear up
would never be that close to the ground, unless the gear had been forgotten,
but the crucial factor is still that the aircraft would be at APPROACH
speed, and not high speed from a dive....., and a missed approach ALWAYS
climbs at the point of adding power......
Regards,
Nigel Willson
Flying Instructor & Examiner | Airshow Organiser | Display Pilot
Mobile:
+44 (0)7809 116676
Email:
nigel.willson(at)yakdisplay.com
Web:
http://easyppl.com
http://greatbritishairshows.com
http://yakdisplay.com
--
| | - The Matronics Yak-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?Yak-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
