Originally published at: South Africa Rule Could 'Decimate' GA with Mandatory Overhauls - AVweb
Long-exempted rule requires engine overhauls at 12 years, regardless of condition or hours logged.
The engine manufacturer does say,_____hrs or 12 years.The “air regulation”is problay just based on that
Tis my understanding that some US shops will not annual a plane whos engines exceed the 12 year rule. I think an average GA plane usage, private use, averages 60 hours a year. That would only be 720 hours in 12 years, about time for a TOP overhaul, not a major.
I suppose it’s a cold comfort that our FAA isn’t the stupidest aviation regulator in the world, although there are times it seems like it. On the whole, it’s harder (read: “more expensive”) to be a private aircraft owner everywhere else. Find a good, healthy A&P/IA, trust its judgement, feed it well, and you’ll fly safely, and more importantly, legally, for years.
I think a rule such as that may have some merit with regard to commercial GA operations but does not make sense for noncommercial operations. Mechanical failure of all types account for about 15% of all GA accidents (Avweb.com). Engine related accidents occur at a rate of 0.21/100,000 hours (Avweb.com). That equates to an engine failure about every 500,000 hours of operation. It is difficult to find data relevant to how often the engine’s age is a factor in the failure, most studies focus on maintenance and maintenance inspection errors as the cause of failure. One study found that there was a 33% higher chance of engine failure in the first hour following an inspection. That is a good reason to consider yourself a test pilot on your first flight after any engine maintenance of an annual inspection. There is little data to indicate that the age of the engine is a significant factor in it reliability if it is well maintained.
Just got installed news OH big Boi continental. Bottom was 20 years old.. As was the TAWS card.
Top done about 1000 prior, Hobbs was approaching 3k.
Comps were fine.. But bleeding oil even after ring flush. Mechanics start getting resistant to sign off..
Paging Mike Busch to the white phone..i euthanized because it wasnt worth doing another top only.
Setting a random rule on years is just dumb really. SA is hosed and corrupt AF but it is a beautiful country (cape, safari, etc)
Maybe it is time that they read: https://reliabilitywebfiles.s3.amazonaws.com/Reliability+Centered+Maintenance+by+Nowlan+and+Heap.pdf
Lessons were learned in WW2. I guess people have short memories.
tl;dr: Screwing around with a complex mechanical device just because the “clock” said so, is more likely to cause problems then to fix them.
“A major question still remained, however, concerning the relationship between scheduled maintenance and reliability. Despite the time-honored belief that reliability was directly related to the intervals between scheduled overhauls, searching studies based on actuarial analysis of failure data suggested that the traditional hard-time policies were, apart from their expense, ineffective in controlling failure rates. This was not because the intervals were not short enough, and surely not because the teardown inspections were not sufficiently thorough. Rather, it was because, contrary to expectations, for many items the likelihood of failure did not in fact increase with increasing operating age. Consequently a maintenance policy based exclusively on some maximum operating age would, no matter what the age limit, have little or no effect on the failure rate.”
Given the higher risk of engine failure just AFTER major work, this ruling should result in an increase in accidents - all at once, as people comply. Fun!