Beyond those tasks, the most notable work-item planned for this year is an inspection of the McCauley constant speed propeller. The prop was overhauled in conjunction with the 2005 Annual Inspection – the first year N631S spent with us – and so it now has about 1,200 hours and eight years SPOH. McCauley holds that the recommended TBO (Time Between Overhauls) is 2,000 hours or seven years, whichever first elapses.
I feel no compulsion to overhaul components at some arbitrarily selected calendar time or time-in-service, as I'm a firm believer in maintenance "on condition". N631S's Continental O-470U engine has a recommended TBO of 2,000 hours or 12 years. The latter mark has long passed and I will cheerfully let the former pass unremarked as well, so long as the engine is talking to me and saying, "I'm fine, boss...let's go fly." And it will do so through spectroscopic analyses of the oil, visual inspections of the filter media and borescope inspections of the cylinders and valves. Ah, but the propeller presents a different problem.
That said, I don't want to "overhaul" the propeller. In the world of aviation, the word "overhaul" has a very specific (and expensive) meaning. It means that you drag out the manufacturer's overhaul manual and do everything that it says to do. But N631S's prop was overhauled back in 2005 and since then has accumulated about 60% of the hours McCauley assigns for TBO. It's just nicely broken in, from the perspective of hours in service, and I'd argue that an overhaul would be premature. My concern is directed more toward the notion that non-metallic parts wear and rubbery things deteriorate more in step with the calendar than with the Hobbs meter. So I've asked Three Wing to take the prop off and send it to New England Propeller (who did the overhaul in '05) with instructions to "IRAN and Reseal". That means, "Inspect and Repair As Needed (to serviceable condition) and renew all fluid seals". Once that is done, I'll happily run the prop for another 1,000 hours before sending it off for "Overhaul".
I stopped at Three Wing this morning and spoke with Tony. He'd done the maintenance run-up and found nothing noteworthy. The cylinder leakdown test had gone satisfactorily. Cylinder #2 was a bit weak at 59 psi (on a day where the minimum acceptable result was 46 psi). Tony will continue and I'll be visiting N631S every day for a while.
2 comments:
Spot-on post, Frank and thank you. (Two posts within a week is both unusual and welcome.
At least in theory, I wholly agree with all of your Annual Inspection (and Prop) choices, but I beg to remind you that you and N631S are far from the typical GA aircraft/pilot combination. You have a hefty and likely cost-saving advantage over most plane/pilot combinations; I hope that lesser experienced owner/pilots take your words with an acknowledgment of your unique relationship. Among the items to be noted...
1. You own your aircraft and have done so for some years.
2. You are an IFR-rated pilot and Use Those Skills on a regular basis - not just in the currency simulator - but in real flying.
3. For the most part, you fly the same N-S and S-N route on a very regular basis; if anyone knows the entire list of glide-slope available fields along that route by memory, you do.
4. You obviously pay close attention to your airplane and you do not fly with errors or malfunctions that you do not understand - or that do not have functionally perfect alternatives.
Heavens yes. Your approach to the annual inspection, necessary maintenance and the occasional overhaul items is sound for you, but not necessarily so for every other GA pilot. Your mileage may vary. The best example is your prop: On a single-spinner airplane it is a truly critical component; when/if it fails, you already know what to do. (Sadly, too many don't.) If you had noticed any irregularities, it would have already been in the shop, so the IRAN procedure seems reasonable and cost effective. (You'll get a fully refreshed prop - and the service folks, their due, next year...) So I'm left with only a single question, sir. Replacing expired landing and taxi lights is well within the tasks authorized as safe for owner/pilots to execute, perhaps with or without a designated examiner's inspection. Why not? Lack of time is understandable. I'm just guessing here, but lack of ability is far less convincing. It is mostly the long duration of the MEL'd item(s) that I ask about. Perhaps you don't fly when those lights might become essential, but as an IFR pilot who frequently uses his IFR ability, who knows what might be necessary? I'm sure that there are perfectly good reasons for deferring these items for months, but I don't understand what they might be. What small points am I missing? I'm just curious and nosy as hell! Your posts directly related to your flying and your flight planning, the outs, alternates and obvious inclusion of plans B, C and D are obvious. In that context, I don't understand flying more than a couple of convenience legs with some important lights MEL'd. Your thoughts are welcome, but you've still got my salute without a response. To repeat, one fine blog! -C.
Hi, Craig!
Let me address your comments about the taxi and landing lights. First, the taxi light failed just days after I did the last oil change. I wasn't moved to drop the cowling again (req'd, and a mild PITA) to replace it, so N631S and I soldiered on with just the landing light. (Incidentally, the lights are in fact identical but wired so that the taxi light switch turns one on and the landing light switch turns both on.)
Fast forward to a couple of weeks ago, and the landing light joined its cross-cowling sibling. But by that time the season had advanced enough so that I was getting to VKX on Friday evening at twilight or sooner. So, I was comfortable deferring replacement of both lights to the annual.
For any decision of this sort I ask myself two questions: Is it smart? And, is it legal?
As to smart...my old instructor Bob Parks insisted that I do most of my night landings without the landing light. His philosophy was that it will certainly fail just when you need it so you'd better not need it. I'm perfectly happy to land on any lighted runway without the landing light (grass strips, not so much -- but those tend to be "day VFR" anyway). To me the landing light is more about day collision avoidance than night illumination. I will add that if the landing and taxi lights are inop, you have to taxi VERRRY carefully.
As to the legalities, 14 CFR 91.205, titled "Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements" says in section (c) that "For VFR flight at night, the following instruments and equipment are required: ...(4) If the aircraft is operated for hire, one electric landing light." emphasis added.
Since N631S is not operated "for hire", I'm legal without the landing light. (Incidentally, the IFR section of the reg does not increase the requirement.)
Also, as an aside, N631S (in common with most GA aircraft) does not have an MEL. If items not on the required equipment list in 91.205 go toes-up you need to placard them as "Inop" i.a.w. 14CFR91.213. Then you can go fly.
Take care, Craig, and thanks for your comments,
Frank
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