For the past 5 years or so, I’ve been performing the Annual Inspections on a friends’s very nice Cessna Centurion.
This year he elected to take it to a very reputable and well respected European Maintenance facility.and once all the inspections panels were opened up and the interior out, I would come over and perform the formal Inspection.
The day before I was to go to the shop for the inspection, my friend called saying the shop performed a compression test and found the #3 cylinder at 42psi and #1 @ 48 psi. The shop’s lead manager advised my friend that they should remove and overhaul the #3 cylinder.
He was not happy and was perplexed since he has a full digital engine monitor, has had almost no problems with the cylinders and all was well just 95 hours before at the last Annual Inspection.
I showed up at the shop early the next day and immediately inspected the engine and borescoped the #3 cylinder. Unfortunately, the borescope that was available was an old optical (non-digital) that only had 90° head swivel so it was next to impossible to get a really good look at the exhaust valve. That said, I saw no signs of valve distress.
So I asked for the shop’s compression test set so that I could perform my own test.
Here’s the differential pressure tester I was loaned :
I was shocked .
I asked the mechanic if that was the tester they used and he replied yes and it is what he and the other mechanics used.
I looked on the back and found the only time it was calibrated was 2002 when it left the manufacturer.
I showed the tester to the shop Manager and I got a blank stare – he obviously realized the problem:
both gauges were not zeroed which shows that they are way off calibration !
He went to the tool shed and produced a brand new tester and I went on to test all 6 cylinders.
… and what do ’ya know , # 3 had 62psi/80 , # 1 was 68psi/80 !
The rest of the cylinders all tested 10 to 20 psi HIGHER than what the mechanic found with the old gauge.
I looked at my friend (another American ex-pat) and said :
" Remember what Ronald Reagan famously said to Mikhail Gorbachev :
“Доверяй, но проверяй " Trust, but verify "This is impossible. I know this company. Very reputable. Half of the European IFR tourer crowd spends their AMUs (aviation monetary units; 1 AMU = $1000) in there. They are EASA 145. Uncalibrated equipment cannot exist. But this is not uncalibrated; this is completely brainless. But that’s impossible too because brainless mechanics cannot exist in an EASA145 facility. Not possible! You must have photoshopped that photo…
The sad truth is that the mechanic was not aware of the procedures spelled-out on Continental’s SB03-3 and did not know what the main orifice was used for either …
The other common error I think is using the wrong sized orifice for the cylinder bore: 0.04" for < 5" and 0.06 for > 5"
I guess they just got shut down on their biggest Milk-cow = Cylinderchanges.
“Sir. Your cylinder nr 5 has a low compression. 58/80. I recommend you replace all 6 while we are first in there. Should save you a lot of money in the future”
Whatdoyousay!!!!!! Shall we!!!!!!!!!!!!"
I thought Continental engines had low compressions because they don’t compress the mixture. They just suck it in and let it expand.
The problem with reporting this kind of thing is that if you are based there and the maintenance company is involved in the airfield, you might get chucked off the airfield. A well known UK GA personality got chucked out of Fairoaks after he filed an MOR having got his glideslope wired upside down. So most people won’t say anything. And in this particular case the company is held in such an incredibly high regard by its countrymen that questioning its competence is sacrilege.
Peter wrote:
A well known UK GA personality got chucked out of Fairoaks after he filed an MOR having got his glideslope wired upside down.
I take it this alleged incident took place when the previous maintenance company (then owned by the former airfield operator) were still in business? Certainly hasn’t happened whilst we’ve been there since 2011!
Yes; correct. It wasn’t yours.
I forgot to mention: the shop where this happened was getting an EASA Audit whlist I was there !
Being fairly new to ownership, I already learnt some of that when the plane came with a fresh ARC/annual out of the CAMO EASA145 etc shop.
Brakes wrongly purged, not properly working.
Stall warning defunct…
The previous owner had brought it there and paid for it. Needless to say, my trust is somewhat gone with these guys…
