Auburn University aircraft problems

G

gacoon

Pre-takeoff checklist
Joined
Mar 30, 2015
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191
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S50 and KDVT
Display Name
Gerry
Home Airfield
S50 and KDVT
Whats going on at Auburn University. Half their fleet has been grounded for 6 months or more. And the students are not getting flight time and are way backed up. A real mess as I understand it?
 
From reddit
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Wasn’t Auburn testing one of the new fuels?
 
Is the fuel servo part of the fuel injection system?

All of my 172 time was in older carbureted models.
 
Larry in TN said:
Is the fuel servo part of the fuel injection system?

All of my 172 time was in older carbureted models.
Click to expand...
1731430472483.png
The typical injection system as used on the Lycomings. The servo is mounted to the backside side of the throttle body, as you see it at the bottom right, with the "idle valve lever" on it. For the purposes of understanding the fuel regulation and flow, the servo is shown at the top left, with the flow of fuel through it. The regulation system at the bottom left of the throttle body doing the bulk of the fuel flow control. It takes ram air pressure (that varies with airflow velocity) and venturi pressure (that varies inversely with airflow velocity) and uses those against unmetered and metered fuel pressures to get the fuel flow just right for whatever power setting is used. The mixture control allows leaning for altitude or DA, and for idle cutoff.

This system is more complex that that used by Continental. Their system uses a positive-displacement fuel pump that pumps more fuel as RPM increases:

1731431017952.png
 
Dan Thomas said:
This system is more complex that that used by Continental. Their system uses a positive-displacement fuel pump that pumps more fuel as RPM increases:
Click to expand...
Thanks for all the detail, Dan. I think the newest 172 I've flown was built in the 1980s.
 
Mentions "contaminated servos" and specifically bad O rings. Bendix RSA servos have millions of hours of reliable service. That suggests somebody is doing something funky.
 
Ed Haywood said:
Mentions "contaminated servos" and specifically bad O rings. Bendix RSA servos have millions of hours of reliable service. That suggests somebody is doing something funky.
Click to expand...
It also sounds like the failed servos were isolated to a particular vendor, and that they were sourcing them elsewhere.

Sounds to me like a reasonable response, yet half of the instructors are concerned about safety. Either there are some serious safety culture issues there, or Chicken Little is running rampant.
 
I was quite impressed with the well-done written article.
 
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