I often hear of owners or syndicates who are grounded for 2-3 months at the Annual, which to me sounds like something went badly wrong e.g. parts needed but the maintenance company were not told / didn’t find out / didn’t order them till too late.
G-reg aircraft suffer the additional 150hr service which is almost a full Annual.
Then you get unscheduled downtime… is this statistically worse on old planes or does it really depend on attitudes to maintenance once the plane is past a certain age (say 25 years)?
The year and 8 months I was a member of a group, the aircraft was out of action probably a year. It took 9 months to sort the brakes! I lost the will to live and baled out of the group. Miss the aircraft and the strip but hey ho, lifes to short to wait around for things to get better. 
The liberty to do one’s own maintenance is the main reason I prefer to fly an ultralight. If I am grounded – as does happen – at least I can see exactly where the blocking factor is. Plus of course maintenance becomes a lot easier to schedule AND a lot less expensive – if you don’t count your hours. I was once grounded for a couple of months though after breaking the prop and nosewheel strut after landing.
Peter wrote:
Then you get unscheduled downtime… is this statistically worse on old planes or does it really depend on attitudes to maintenance once the plane is past a certain age (say 25 years)?
Depends on the plane. Older planes are typically simpler in construction and systems, and less regulated (if at all) by limitations section of the MM, plus new ADs are less likely. So from that point of view they are easier to maintain airworthy. That’s why I prefer older, un-‘supported’ airframes with generic engine, brakes, AN hardware, instruments etc. OTOH, if you have an old, complex airframe with unusual engine(s), brakes, hardware, instruments etc it can certainly go the other way.
My aircraft is usually away for a month or 5 weeks come permit revalidation, but that’s more because taking the aircraft away to Spanhoe to have it done and my annual trip to the USA coincide, so I’m actually not there to fly it anyway!
I think it can depend on whether the aircraft is maintained at the airfield where it is based, (and where pressure can be more easily exerted.)
Our last aircraft was maintained at our base airfield and an annual typically took two to three weeks to complete.
Our current aircraft is maintained well away from base and the last two annuals have taken nearer three months…….
flybymike wrote:
Our last aircraft was maintained at our base airfield and an annual typically took two to three weeks to complete.
Mine is (no longer) maintained at its home airfield and an annual takes 2 days, with some bad luck 3 days (ok, with some very bad luck indefinitely 
). The aircraft is complex with turbo, retractable, etc. Why would an annual take 2-3 weeks?
My annuals (owner assisted at shop at home) take 2 days if everything is okay and no components have to be changes, and sometimes 3 days if there’s a lot to repair, change. 2-3 weeks is ridiclous.
Flyer59 wrote:
My annuals (owner assisted at shop at home) take 2 days if everything is okay
The Cirrus 100 Hour / Annual Inspection per the MM, is a solid 25 Hours, no squawks.
That probably depends on how fast you work. We always manage to do it in two days.
