Inoperative Instruments and Equipment

Section 91.213 — Inoperative instruments and equipment — establishes the framework for operating with inoperative equipment. It has two paths: the MEL path (paragraphs a-c) and the non-MEL kinds-of-operations-equipment-list path (paragraph d).

MEL path (paragraphs a-c): For aircraft with an approved Minimum Equipment List (MEL), inoperative equipment may be operated per the MEL's specified conditions, time limits, and procedures. The MEL is a FAA-approved document specific to the aircraft type and operator.

Non-MEL path (paragraph d): For small piston-powered aircraft (typically GA singles and twins) without an approved MEL, the aircraft may operate with certain inoperative equipment IF:

• (1) The inoperative instrument/equipment is NOT:
  • (i) Part of the VFR-day equipment in § 91.205(b)
  • (ii) Indicated as required on the aircraft's type certificate equipment list or kinds-of-operations equipment list for the kind of flight
  • (iii) Required by § 91.205 or any other rule in this Part for the specific kind of flight
  • (iv) Required to be operational by an airworthiness directive
• (2) The inoperative instruments/equipment are:
  • (i) Removed from the aircraft, the cockpit control placarded, and the maintenance recorded in accordance with § 43.9; OR
  • (ii) Deactivated and placarded INOPERATIVE
• (3) A determination is made by a pilot (who is certificated and appropriately rated) or by a certificated and appropriately rated maintenance person that the inoperative instrument/equipment does not constitute a hazard to the aircraft.

The 'pilot determination' under (d)(3): A pilot can determine that an inoperative item is not a hazard — but the pilot has the legal responsibility for that determination. If a passenger door light fails, the pilot can placard it inop and continue. If an airspeed indicator backup fails on an IFR-equipped twin during enroute, that's a different determination.

The 'remove or placard' requirement: Inop items must be either removed AND the action logged per § 43.9, OR placarded INOPERATIVE. Just ignoring an inop item is not legal.

Reference: AC 91-67 on MEL procedures; FAA Order 8900.1 Volume 4, Chapter 4 on MEL approval.

MEL vs the § 91.213(d) Deferral Procedure — Decoded

Walk into a hangar conversation about an inoperative gauge and you'll hear two phrases used as if they're interchangeable: "we'll MEL it" and "we'll defer it under 91.213." They are not the same procedure. They live in two different worlds of § 91.213, and which one applies to your airplane depends on a single question most pilots never bother to ask.

Does your aircraft have an FAA-approved Minimum Equipment List?

Most Part 91 GA piston singles do not. An MEL is a formal document approved by the responsible Flight Standards office, issued with a letter of authorization specific to your tail number — not a generic list, not the MMEL the manufacturer publishes, not something downloaded from a forum. If you don't have the letter of authorization, you don't have an MEL. Full stop.

Here's the branching decision tree:

The MEL categories matter when you're on the MEL path. Category A items have a repair interval specified per item. Category B is three calendar days. Category C is ten calendar days. Category D is 120 calendar days. The clock starts the day after the malfunction is recorded. Miss the interval and the airplane is grounded until it's fixed — not "until the next annual."

The honest framing of § 91.213(d): it is a real procedure a pilot can execute in coordination with maintenance. It is not a "fly with anything broken" license. The mechanic logbook entry under § 43.9 is a hard requirement — not a suggestion, not "we'll catch it at the next annual." Either the item is removed and a maintenance entry is logged, or it's deactivated and placarded INOPERATIVE and a maintenance entry is logged. A placard alone is not compliance. A logbook entry alone is not compliance. You need both.

And the equipment lists that gate the (d) procedure cross-reference outward — that's the part that trips pilots up. § 91.205 is day VFR, night VFR, and IFR equipment. § 91.207 is the ELT. § 91.213 is the deferral procedure itself. You can't defer an item under (d) without checking all three.

What an Examiner Asks About § 91.213

This reg shows up on private, instrument, commercial, and CFI checkrides — usually as a scenario the DPE drops into preflight. They're not looking for a recitation of (a) through (e). They're looking for whether you can walk the (d) procedure end-to-end without skipping a step.

• "Your fuel gauge for tank #2 just broke. Can you fly?" Walk the (d) checklist out loud. Fuel gauges are required by § 91.205(b)(9) — one per tank, day VFR. That's the floor. You can't defer it under (d) because it's required equipment. The airplane is grounded until the gauge is repaired, replaced, or you have an MEL that authorizes deferral.
• "What's the difference between the MEL path and the (d) procedure?" An MEL is FAA-approved, tail-specific, comes with a letter of authorization, and uses category A/B/C/D repair intervals. The (d) procedure is for aircraft without an MEL — verify the item isn't required by 91.205, AD, or KOEL; placard it INOP; get a mechanic entry. Two different worlds. Most light GA flies under (d).
• "What's KOEL?" Kinds of Operations Equipment List — published in the aircraft's POH or AFM. It lists what equipment must be installed and operative for each kind of operation the aircraft is certified for (day VFR, night VFR, IFR, icing, etc.). It's part of the type certificate's operating limitations. Under (d) you must confirm the inop item isn't on the KOEL for the flight you're about to make.
• "Do you need a mechanic involved?" Yes. The (d) procedure requires either removal of the item by a certificated and appropriately rated maintenance person, or deactivation, with a maintenance record entry per § 43.9. A pilot placard with no logbook entry is not compliance.
• "What's the one check pilots usually forget?" The AD check. Pilots remember 91.205 and the KOEL. They almost never check airworthiness directives on the inop component. If an AD requires the item, you can't defer it under (d) — even if 91.205 doesn't list it and the KOEL doesn't require it for your flight.

Deferring an Inop Item, Under § 91.213

You arrive at the airport, walk out to a Cessna 172 for a day-VFR personal flight, and during preflight the landing light won't come on. Aircraft has no MEL — typical light single. Here's the (d) procedure end-to-end.

Step 1 — Check § 91.205. The landing light lives at § 91.205(c)(4), in the night VFR list, and only when "operating for hire." Day VFR personal flight: not required by 91.205. First gate cleared.

Step 2 — Check the KOEL. Open the POH to the Kinds of Operations Equipment List. Confirm the landing light is not listed as required for day VFR. In a 172 it isn't. Second gate cleared.

Step 3 — Check ADs. Pull up the airworthiness directives for the aircraft and the landing light installation. No active AD on the landing light. Third gate cleared.

Step 4 — Placard. A placard reading INOPERATIVE goes on the landing light switch — visible to the pilot, not hidden in a panel. The placard is not optional and not a sticky note.

Step 5 — Mechanic logbook entry. A certificated and appropriately rated mechanic either removes the landing light circuit and makes a maintenance entry per § 43.9, or deactivates it and logs the deactivation. The entry records what was done, when, and by whom. The pilot does not write this entry.

Step 6 — Fly. Day VFR, personal flight, with the placard in place and the maintenance entry signed. Legal under (d).

Change one variable and the procedure changes. If the same flight were after sunset and the operation were for hire, § 91.205(c)(4) requires the landing light — first gate fails, no deferral. If the flight were IFR and the inop item were the attitude indicator, § 91.205(d)(8) requires it — first gate fails, no deferral. The (d) procedure is rigorous, but it's narrow. Most primary flight instruments don't survive it.