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Instrument Repair
Posted: Mon Oct 01, 2018 6:24 pm
by 170C
This seems to be my year to fix things! Get one fixed and something else goes afoul.
My DG (Edo-Air) quit on me Saturday. Got 3 " of vacuum at 1800 rpm, artifical horizon works and vacuum gauge works so I'm reasonable sure the DG is kaput. Had it repaired in early 2016 by Nu-Tec in Augusta, KS ($388.00). Thought it should have lasted longer, but what do I know? I have used Century Instruments in Wichita, KS in the past and see that Rudy Aircraft Instruments in Rudy, AR repairs as well. Appears most shops advertise around $360 to OH a DG. There are several shops in KS. Must be due to the two major aircraft mfg's in the area.
Would welcome any suggestions for shops others have used. Would be nice to replace my unit with an electric DG, but around $2500 is a bit steep!
Re: Instrument Repair
Posted: Mon Oct 01, 2018 8:16 pm
by ghostflyer
How about fitting a Garmin G5 ,no vacuum issues,no moving parts costs about the same as a electric Dg.
Re: Instrument Repair
Posted: Mon Oct 01, 2018 10:44 pm
by Ryan Smith
ghostflyer wrote:How about fitting a Garmin G5 ,no vacuum issues,no moving parts costs about the same as a electric Dg.
Because fixing a vacuum DG is about $2300 less...
Re: Instrument Repair
Posted: Mon Oct 01, 2018 11:10 pm
by 170C
Ryan, you are so correct!
Re: Instrument Repair
Posted: Tue Oct 02, 2018 12:15 am
by GAHorn
Frank, it might not be evident but if you open up the vacuum system for a gyro repair/replacement it's generally considered good practice (and usually a warranty-requirement) that the system filter also be replaced. That might explain the short life of the last overhaul... or it might simply be poor luck. Who knows...
... anyway, my personal favorite shop is Aircraft Quality Instruments in Wichita, KS
http://flyaqi.com/
(800) 942-9938
(family operation, former combat allies in Viet Nam) Excellent work and turn-around and also one of the very few who will still overhaul AN gyros.
Re: Instrument Repair
Posted: Tue Oct 02, 2018 12:54 am
by c170b53
Second George’S pick. One instrument they fixed for me was damaged in shipping and they repaired that plus shipping with no further cost to me
Re: Instrument Repair
Posted: Tue Oct 02, 2018 1:08 am
by sfarringer
Doesn't 3 inches of vacuum seem a little low?
I thought gyros were meant to have at least 4.5 inches?
Re: Instrument Repair
Posted: Tue Oct 02, 2018 1:53 am
by GAHorn
sfarringer wrote:Doesn't 3 inches of vacuum seem a little low?
I thought gyros were meant to have at least 4.5 inches?
Modern, 3-1/8" so-called "pictorial" gyros do require more vacuum than the original AN types. 4.5 vs 3.5 approx.
Re: Instrument Repair
Posted: Tue Oct 02, 2018 2:18 am
by 170C
The 3” of vacuum was sitting outside my hangar at 1800 rpm. Next day or so
I’ll fly it to see what I get in flight at normal rpm (2500).
Thanks for the repair shop suggestions.
Re: Instrument Repair
Posted: Thu Oct 04, 2018 4:48 pm
by cessna170bdriver
gahorn wrote:...
Modern, 3-1/8" so-called "pictorial" gyros do require more vacuum than the original AN types. 4.5 vs 3.5 approx.
A bit off topic but, George, do you have any hard data on the CFM flows required by the modern vs. AN gyros? (Vacuum pressure is only part of the equation...)
Re: Instrument Repair
Posted: Fri Oct 05, 2018 2:25 pm
by GAHorn
I'm not at home (again) so cannot access my instrument repair data today. I'm trying to determine what you are seeking, Miles.
Considering the physical restraints of modern gyros should give us a clue, however. It seems to me that the inlet size of those instruments, factored by the vacuum recommendation of the instrument mfr's is what would define the CFM which flows thru it.