Understanding Aircraft Maintenance Regulations

4 min read

maintenanceIn aviation we often use memory aids to help us remember the ever growing list of items a pilot should know.  This can include everything from checklist items, to required equipment, to regulations.  One of the most popular memory aids that instructors use for their students are mnemonics.  One that I would like to discuss is the memory aid “AVIATE” used to help pilots recall the maintenance inspection requirements for GA flights.

The potential short-coming with using a mnemonic like “AVIATE” is that not every item referenced in the mnemonic applies to every circumstance.  As an example, many students find it difficult to differentiate what maintenance requirements apply to VFR versus IFR flight.  A common reason why students have a hard time in this particular application is because the student has NEVER actually read the regulation.

Many student pilots read the FARs, in particular 14 CFR Part 61 and 91, but tend to focus on the regulations in part 91 up to 91.205 – required equipment.  Beyond that section seems be a black hole of knowledge for many student pilots and licensed pilots alike.  Here is a good reference to help you remember and learn the actual maintenance regulations using the mnemonic “AVIATE”.

annualAnnual – Every aircraft operated under part 91 regulations is required to undergo an “annual” inspection in accordance with FAR part 43 every 12 calendar months.  This regulation applies to VFR and IFR flying and is not dependent on how the aircraft is used (i.e. for hire).   The applicable regulation is actually FAR 91.409(a).

VOR – In order to use VOR navigation in IFR flying, the accuracy of the device must be checked every 30 days.  There is a list of the types of inspections that can be performed to check its accuracy (all covered in the regulation below), but the key element of this accuracy check is that it only applies to IFR flying.  The complete regulation and required inspection types can be found in FAR 91.171.

100 Hour – In certain operations when an aircraft is being used “for hire” and specifically, for an aircraft used in flight instruction for hire, the aircraft is required to undergo a “100 hr” inspection every 100 hrs of engine operation (normally a tachometer time reading).  This would apply to either a VFR or IFR flight, but is specific for flights being operated for hire.  There are some additional rules that you should review concerning how the time is measured and when the inspection must be completed, but those can be found in FAR 91.409(b).

Altimeter/Pitot-Static System Check – Each altimeter and static pressure system must undergo an inspection to ensure accuracy and compliance with standards every 24 calendar months if the aircraft is to be used for IFR flight.  There are no circumstances where this inspection is required for a VFR flight.  Additional information can be found in FAR 91.411.

Transponder – Transponders are required to be inspected for accuracy and standards every 24 calendar months, if required.  This requirement is actually two-part.  FAR 91.413 specifies the inspection interval of 24 calendar months, but it does not state when you are required to use a transponder.  The regulation references FAR 91.215 which states when and where you are required to have an operating transponder and in which mode.

For most aircraft and students, when the regulations specify a “Mode A” transponder, think turning the transponder to ON, and when it requires a “Mode C” transponder, think turning the transponder to ALT.  Given these circumstances, this regulation applies to VFR and IFR flying.  There are some limited exceptions for aircraft that do not have a transponder due to never being certified with an electrical system (i.e. Piper Cub). These aircraft are exempt from this inspection.  Although transponders are only required in certain airspace, it is always a good idea to have it on and in Altitude Encoding mode (ALT or mode C) whenever possible for traffic avoidance.

ELT – Every aircraft (with some limited exceptions) is required to have an  Emergency Locator Transmitter (ELT), and that unit must be inspected every 12 calendar months as found in FAR 91.207(d).  This regulation applies to both VFR and IFR flying.  In addition to the required 12 calendar month inspection, you should also be familiar with FAR 91.207(c) which states requirements for battery replacement and recharging under specific conditions (1 hour of cumulative use or half of the battery useful life) and is just as important as the 12 calendar month inspection.

This guide is a good overview of the rules but is no replacement for reading the  regulations.  If you have questions about these regulations, make sure and talk to your instructor to get clarification or contact the chief instructor or local FAASTeam representative at your airport.


2 replies
  1. Ken leonard says:

    ‘Understanding maintenance regulations’ was quick, clear and well said. I’ll remember with the mnemonic ‘AVIATE’ and appreciate the author pointing out the exceptions. Particularly for light sport and experimental, there is lots of ‘opportunity’ for more clarifying articles on various interpretations of FARs.

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