FAA’s Safety Continuum

Sep 1, 2019

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The Friendlies are remarkably friendly to Part 91 folks

Aircraft owners and pilots love to bash the FAA. We grumble and whine about all the labyrinthine regulations and requirements the Agency burdens us with, and how much it increases our complexity and cost of flying. I’m occasionally guilty of this myself—witness my “Double Standard?” column in last month’s AOPA PILOT in which I kvetched about the FAA’s failure to require A&Ps to undergo recurrent training and re-evaluation.

In truth, we Part 91 operators have it pretty darn good compared with our brethren in almost every other nation on the planet. We also have it exceptionally good compared with charter operators (Part 135) or air carriers (Part 121) or large aircraft in non-commercial operations (Part 125).

This isn’t by accident. It’s in accordance with one of the FAA’s most fundamental guiding principles—something the Agency polysyllabically calls the “Safety Continuum.” 

 “Safety Continuum: The level of safety established by regulation, guidance and oversight that change based on risk and societal expectations of safety. The safety continuum applies an appropriate level of safety from small UAS to large transport category aircraft. The differing level of safety balances the needs of the flying public, applicants and operators while facilitating both the advancement of safety and the encouragement of technological innovation.”

Simply stated, this says that although the FAA’s primary job is to ensure aviation safety, it recognizes that different kinds of aircraft and operations require different levels of safety. Aircraft that carry lots of people need to be safer than ones that carry just a few people (like the ones most of us fly), and those need to be safer than UAS that don’t carry any people. Public common carriers (e.g., airlines) need to be safer than contract carriers (e.g., charters), and those need to be safer than private carriers (e.g., GA pleasure or business). Pretty commonsense stuff.

Most of us know that the operating rules are far more stringent for commercial operations under Part 135 or Part 121 than they are for us Part 91 folks. Aircraft equipment and operating limitations, weather requirements, fuel requirements, crewmember qualifications and recurrent training and testing requirements (including checkrides and drug tests) are all vastly more demanding than what we put up with. Less well understood are the dramatic differences in maintenance requirements.

FAA Maintenance Requirements

Although the regulations concerning what maintenance is required are quite complicated and somewhat obscure, the basics are straightforward:

Part 121/135 operators are required to comply with both the inspection program and the maintenance program recommended by the aircraft manufacturer (or alternative FAA-approved inspection and maintenance programs).

Part 91 operators of multiengine turbine airplanes or large airplanes (over 12,500 pounds) are required to comply with the inspection program recommended by the aircraft manufacturer (or an alternative FAA-approved inspection program) but are not required to follow any particular maintenance program.

Part 91 operators of piston or single-engine turbine airplanes (12,500 pounds or less) are not required to follow any particular inspection or maintenance program. They require only a generic annual inspection every 12 months. (If the aircraft is used to carry passengers for hire or to give flight instruction for hire, it also requires generic 100-hour inspections.)

To understand what this means, it’s important to understand the distinction between an inspection program and a maintenance program. This can get a bit confusing, because FAR 1.1 (“Definitions”) says:

Maintenance means inspection, overhaul, repair, preservation, and the replacement of parts, but excludes preventive maintenance.

Thus, “inspection” is one sort of maintenance—the other sorts being overhaul, repair, preservation and the replacement of parts—but the regs never explain what inspection means. To unravel that, you must drill down into some rather obscure FAA orders, interpretations and memoranda. 

Particularly illuminating is FAA National Policy Notice 8900.410 titled “Clarification of Inspection and Overhaul Requirements Under Part 91.” This seven-page memorandum issued by FAA Headquarters in March 2017 was intended for FSDO Airworthiness Safety Inspectors (to help clear up their confusion about this stuff) but makes very illuminating reading for owners of Part 91 aircraft and the A&P mechanics who work on them. (You can find it online at faa.gov/documentLibrary/media/Notice/N_8900.410.pdf.) Here are a few excerpts from this Notice:

Inspections are visual examinations and/or manual checks to determine the condition of an aircraft or component.

Inspection programs refer to a list of scheduled inspection items and associated intervals whose main purpose is to determine the condition of the aircraft and its components. In other words, they are scheduled items done at a defined interval to check for hidden damage and continued serviceability.

Maintenance personnel should not confuse an inspection program with the elements that make up a more extensive maintenance program. An inspection program will only capture a list of scheduled inspections whereas a maintenance program will encompass many elements, to include inspections, overhaul requirements, repair schemes, [corrosion prevention], and the scheduled replacement of parts.

Overhauls are a form of maintenance, not inspection, and are not included in an inspection program. Overhauls are part of the maintenance program. Part 91 operators are not required to comply with a manufacturer’s maintenance program; as such, overhauls are not mandatory for part 91 operators.

Part replacement is a part of the overall maintenance program and are not to be included in an inspection program [unless the inspection destroys a part, such as cutting open an oil filter].

With some exceptions, compliance with manufacturer service bulletins is not required to be accomplished … for part 91 operators.

So, if you fly a Part 91 piston airplane or a single-engine turboprop or jet, you don’t have to comply with any of the manufacturer-specified inspection or maintenance intervals if you don’t want to. If you fly a multiengine turbine (like a King Air or Citation) or a large airplane (like a DC-3) under Part 91, you are required to comply with the manufacturer’s inspection program (typically consisting of various “phase checks”) but you don’t have to comply with the manufacturer’s maintenance program (including TBOs and scheduled parts replacement) if you don’t want to. For any kind of Part 91 aircraft, you don’t have to comply with manufacturer’s service bulletins if you don’t want to.

There are a few exceptions: If the FAA issues an Airworthiness Directive mandating compliance with some manufacturer-specified inspection or maintenance item or service bulletin, then you must comply—ADs are non-negotiable. Also, if you fly a newfangled Part 23 aircraft like a Cirrus or Diamond or Corvallis/TTx whose maintenance manual contains an FAA-approved Airworthiness Limitations Section, then you must comply with anything in that Section—such as the 10-year chute repack and rocket refit for the Cirrus SR22—provided it was in effect on the date your airplane rolled off the assembly line. (Revisions to the maintenance manual are not retroactively compulsory for aircraft manufactured prior to the revision.)

What About ICA?

In addition to the usual maintenance manuals, some aircraft, engines, propellers and appliances may be subject to manufacturer-specified “Instructions for Continued Airworthiness” (ICA). This sounds intimidating, and many owners and A&P mechanics believe that the regulations require ICA to be complied with. Not so.

It turns out that the rules that govern Part 91 compliance with ICA are precisely the same as the rules that govern maintenance manuals, service bulletins, and other manufacturer-specified maintenance guidance. If you fly a Part 91 King Air or Citation or DC-3, you’re required to follow any inspections set forth in applicable ICAs, but not any other sort or maintenance (such as overhauls or parts replacement). If you fly a Skyhawk or SR22 or Baron or TBM, you don’t have to comply with ICAs at all—unless an ICA contains an FAA-approved Airworthiness Limitations Section (most don’t) in which case you are required to comply only with what’s in that Section, but not anything that appears in other sections of the ICA.

Please don’t get the idea that I’m suggesting you ignore all manufacturer’s inspection and maintenance recommendations. I’m certainly not saying that! Some things the manufacturers instruct us to do are sensible and worth doing; other things they instruct us to do are unnecessary overkill. The important takeaway is that the FAA says that almost all the maintenance tasks the manufacturers recommend—inspection checklists, TBOs, preventive maintenance, parts replacement intervals, ICAs—are only recommendations, not requirements, for Part 91 operators. It’s the aircraft owner’s prerogative to do them or not as he or she sees fit.

The FAA takes a remarkably lenient posture when it comes to maintenance requirements for Part 91 aircraft. I know of no other nation that gives this much latitude to owners of small non-commercial aircraft. Is it any wonder that GA in the U.S. is so much more robust and affordable than anywhere else on earth? 

Thank heaven for the FAA’s Safety Continuum philosophy! Let’s give the Friendlies credit where credit is due.

You bought a plane to fly it, not stress over maintenance.

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