Tuesday, April 30, 2013

2013 Annual Inspection (ii)

This year's Annual Inspection, now completed, was an unusual one. And I mean that in a good way. There was very little "emergent" work resulting from the inspection and most of the work effort was focused on items properly classifiable as "maintenance". Even the one major cost item, the inspection and resealing of the propeller (first discussed here) was not the result of a "squawk". The prop was turning just fine when removed from the airframe.

If you wonder what happens when the propeller shop is told to "IRAN & Reseal" rather than overhaul, the log entry for the propeller work is instructive:

"Propeller disassembled, cleaned and visually inspected for red dye oil leak. Replaced all seals and gaskets. Reassembled, set angles, track and balanced. Propeller filled with red dyed oil and pressure tested."

The engine, at 1749.3 hours Since Major Overhaul (SMOH), seems to be holding up very nicely. The pressure drop data is perfectly acceptable (see the chart at left for seven years of data), the filter media were free of metal particles and there were no worrisome indications found by borescope. An oil sample has been sent off for spectrometric analysis but I don't anticipate any bad news from that quarter.

I flew the airplane for a 1/2 hour local test flight last Thursday evening with the only squawk being that the landing lights (both of which were replaced) were inop. As it happens, there is an in-line connector in the wire harness that supplies power to the landing lights and it has to be unmade to remove the lower cowling. In this case, it didn't get re-made when the cowl was re-installed. That minor glitch was remedied the next day and on Friday I flew N631S down to the DC area for the first time in three weeks. Then we flew back, mostly in rain and clouds, yesterday morning. No new problems showed up so I'm ready to call it done.

The only leftover item – which is an expected issue – is the need to adjust the Shadin Miniflo-L fuel computer to correctly interpret the output of the replaced fuel flow transducer. Every transducer is tested by the manufacturer to determine the number of electrical impulses it emits per gallon of flow passing through and that "K-factor" is supplied with the sensor. For this unit, the K-factor is 19.8, meaning 19,800 pulses per gallon. Right now, the computer is reading about 10% high. To correct the condition it has to be removed from the panel and reprogrammed with the new K-factor. Naturally, this can't be accomplished in situ, as that would be far too easy. So sometime soon my friends at Three Wing Aviation Group (check out their spiffy new web site!) will make the adjustment and all will be well.

I anticipate one more post about this year's Annual wherein I'll analyze the final invoice.

2 comments:

Dave Starr said...

I saw on FlightAware.com that you were back in the air, Frank, glad to know the annual wasn't too painful this year. Interested in knowing the details. Fly safe and enjoy.

Frank Van Haste said...

Hi, Dave! There will be some additional detail in a forthcoming post where I will parse the invoice, as I've done after the last few annuals.

Hope all is well for you.

Frank