I am familiar with aircraft which use a Hobbs meter for timekeeping using an oil pressure switch. I am also familiar with aircraft with a recording tachometer.

Less familiar are aircraft which use only a hobbs or similar timekeeping device.

What are the requirement for timekeeping on aircraft with a US airworthiness certificate? Is there a part 23 or other requirement?

  • $\begingroup$ Does this answer your question (assuming you are asking about "time-in-service" for maintenance purposes): aviation.stackexchange.com/questions/80039/… $\endgroup$
    – user22445
    Commented Nov 26, 2022 at 21:04
  • $\begingroup$ Some of the questions touch the topic, but I'm afraid none to date give a satisfactory citation. Requirements are inferred, but the need for a timekeeping device is ambiguous. As far as I have found, the requirements of FAR 91.409(b), as well as other requirements, could be met by fastidious manual timekeeping. $\endgroup$ Commented Nov 26, 2022 at 22:41


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