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5 Answers

Oil change intervals?

Asked by: 6917 views FAA Regulations

Is there any specific regulation that is laid out for oil change intervals for small general aviation aircraft? In my experience, the consensus seems to be that oil should be changed in frequently flown aircraft every 25 to 50 hours. And obviously oil must be changed during the annual inspection, but is this regulatory? Privately operated aircraft are not subject to the 25, 50, and 100 hour inspections as are commercially operated aircraft, but are the oil changes for those commercially operated aircraft regulatory at those inspection intervals specifically? Or are the oil change intervals only bound by the scheduled required inspections? To keep it simple, can anyone cite an FAA regulation that specifically says you must change your oil, and specifically says how often?

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5 Answers



  1. Kent Shook on Jan 03, 2011

    I don’t think you’ll find it in an FAA regulation – If it were in the regs it’d be in Part 43, and I didn’t find anything there specifying an oil change interval. I think the most likely place for it is in the operator’s manual or maintenance manuals for the engine.
     
    In general, I think the engines that have only a screen instead of a filter are supposed to have their oil changed every 25 hours, and those that have a filter should be changed every 50 hours. I’m sure there are probably exceptions, however.
     

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  2. Robert Ericson on Jan 07, 2011

    I had this conversation with our A&P quite a bit this past summer.  Our C-172M had an oil screen installed and was recommended that we change the oil and check the screen every 30-40 hours.  Since we have been flying the aircraft more often this year and switched to an oil filter, our A&P has now recommended 50 hour oil and filter changes.
    Hope this helps.

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  3. Heather McNevin on Jan 30, 2011

    If you have an oil screen, I’d recommend 25 hours.  If you have an oil filter, 50 hours or 6 months.  Oil’s job is to take crud out of the engine and lubricate important parts.  Don’t skimp on that.  Oil change is also a great time to clean the aircraft and check for any leaks or other maintenance issues. 

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  4. Bruce on Apr 21, 2012

    Heather is right on the money. Robert and Kent did well also.
     43.13   Performance rules (general).
    (a) Each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or appliance shall use the methods, techniques, and practices prescribed in the current manufacturer’s maintenance manual or Instructions for Continued Airworthiness prepared by its manufacturer, or other methods, techniques, and practices acceptable to the Administrator,
    So if the manufacture says 25 for screens, 50 for full flowfilters. There you go. No difference in part 91 or 135 maint. It all is done IAW part 65 and 43 for the mechanics standpoint.
     

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  5. FinalFantasy on Jan 13, 2016

    Kent, Robert and Heather are correct but Bruce is wrong because he’s not interpreting 43.13 correctly. There is no regulatory requirement to change oil at any specific interval. Part 43.13 only speaks about “how” to do things not “when”. What 43.13 says is that if you’re going to do it, then you have to do it in a way that the FAA or the manufacturer deems acceptable.
    But nothing that the engine or aircraft manufacturer specifies about “when” has any regulatory impact, unless the FAA says so via an Airworthiness Directive or (for more modern Part 23 registered aircraft) is there is an Airworthiness Limitation in the POH.

    So for instance, it is perfectly legal (and if done correctly it can be perfectly safe too) to run engines past the manufacturer’s TBO, or to change oil less often than the recommended 25/50 hours that the manufacturer recommends. Check out Mike Busch’s webinars on cost-effective maintenance, if you want to really understand what the regulatory obligations of an aircraft owner really are. Most non-owners (including lots of CFIs) do not seem to have a firm grasp of the regs in this area.

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