What are the record-keeping requirements for flight or operational use of an aircraft only flown under Part 91? Rental aircraft always have such a logbook, for obvious reasons, but are privately-owned-and-operated aircraft required to keep such a log by regulation?
91.417 and 43.9 clearly dictate the requirements we often refer to as the airframe, engine, and prop maintenance logs. This is not the same as an aircraft flight log.
AC 43-9C further clarifies the above.
61.51 dictates pilot experience logging requirements. Some of the information recorded in a pilot log is duplicated in the aircraft flight log.
In Canada, this is referred to as a "journey log" and the requirements are explicitly stated in 605.94
AC 91-70B concerns flying in "oceanic and remote continental airspace", but deep in 5.4.1.2 recommends a journey log and references ICAO Annex 6.
ICAO Annex 6 Part I 11.4 defines the "journey log" for commercial flights, and is a "recommendation".
ICAO Annex 6 Part II 2.8.2 similarly defines the "journey log" for general aviation, and is also a "recommendation".