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Inoperative Equipment, FARs and the MEL

I was in the right, front seat of a new Beech Baron. My student, owner of the factory-fresh Beech, had smoothly taken off, beginning a wide, standard-rate turn to the left, away from the airport and toward our practice area. The morning was cool and bright, the sun muted through a thin layer of cirrus clouds far above.

I was in the right, front seat of a new Beech Baron. My student, owner of the factory-fresh Beech, had smoothly taken off, beginning a wide, standard-rate turn to the left, away from the airport and toward our practice area. The morning was cool and bright, the sun muted through a thin layer of cirrus clouds far above.

Turning on course, we both noticed a flashing annunciator light on the glareshield directly in front of the pilot, almost at eye level. "ALT OUT," it flashed -- indication of a failed alternator on the left engine (the Baron has an alternator on each of its two powerplants). Checklist procedure calls for first verifying the true nature of the indication, by looking at the alternator loadmeter for that engine. Strangely in this case, the loadmeter for the left engine showed normal electrical generation -- the alternator hadn't died; something was causing a false indication on the annuniciator.

This presented a wonderful teaching opportunity. All too often a pilot (or sometimes even an entire airline cockpit crew) gets so distracted by a minor irritation like this "lamp driver" failure that airplane control is eventually lost, or the airplane flies into terrain. My student, a wise man, asked me to take the controls for a moment while he checked it out.

Insider's Tip: When handing over control of an airplane, make certain there's no doubt as to who's flying. A formal passing of responsibility requires both pilots acknowledge the exchange out loud. Pilot 1 says: "You have the flight controls," but he doesn't assume Pilot 2 has "got it" until Pilot 2 echoes back, "I have the flight controls." Only then can Pilot 1 turn to other duties.

Pulling out the checklist, my student quickly confirmed that procedure allows continued flight with an inoperative alternator warning light, so I formally turned control back over to him and we continued the flight.

Later in the lesson, as we cruised level using the Baron's autopilot, I asked my student, "After we land at the end of this lesson, can you take off again with the faulty alternator out light?"

"Sure," my student replied warily.

"What other conditions must exist for you to be able to take off with the failed light?" I probed. Certain now I was setting a trap, my student asked to have time to look into it on the ground. Wise man, as we were beginning to be vectored for a practice instrument approach.

But he didn't escape. On the ground I asked again: "Can you take off with the balky alternator annunciator?" That led us into a discussion of Federal Aviation Regulations (FARs), Pilot's Operating Handbooks (POHs), and Minimum Equipment Lists (MELs).

FAR 91.205 lists the equipment that needs to be installed and operable in order for an airplane to be flown legally ... and safely. The "reg" breaks down requirements by the type of flight operation. See FAR 91.205 (b) for more details.

Visual Flight Rules -- Day: Daytime visual flight rules (DVFR) operation requires:

  • basic engine instrumentation;
  • an airspeed indicator, altimeter, and magnetic compass; and
  • if the airplane has retractable landing gear, a landing gear position indicator.

There are further requirements for anticollision lighting, although it may be inoperable on a flight made to a location where repairs will be made. Seat belts and other items are also mentioned. See FAR 91.205 (b) for more details.

Visual Flight Rules -- Night: Nighttime flight under visual flight rules (NVFR) mandates all of the above, plus:

  • approved position lights;
  • an "adequate source of electrical energy" for all installed electrical equipment; and
  • a complete set of spare fuses or three spare fuses of each kind required in the airplane that are accessible to the pilot in flight. (FAR 91.205 (c)).

Instrument Flight Rules (Day or Night): Flight under Instrument Flight Rules (IFR), even if flown in VFR conditions, requires all of the above, and additionally:

  • two-way radio communications and navigational equipment appropriate to the facilities to be used;
  • gyroscopic rate-of-turn, attitude and heading indicators;
  • a slip/skid indicator;
  • a barometrically adjustable ("sensitive") altimeter;
  • a generator or alternator of adequate capacity; and a
  • a clock with sweep second hand or digital presentation including hours, minutes and seconds (FAR 91.205 (d)).

Back to my Baron student... It appears that there's no requirement for an alternator warning annunciator. So he concluded that it's legal for him to depart with this inoperative light.

There's more to Part 91. FAR 91.213, Inoperative Instruments and Equipment, tells us that all installed equipment must be operable for takeoff unless (1) the equipment is not required under 91.205, (2) the equipment is not required to be operative under an Airworthiness Directive, and (3) the airplane's Pilots Operating Handbook does not otherwise require the equipment be in working order (more on that in a moment).

91.213 further states that, if flight is allowed with the equipment out of service, the device must be either:

  • removed from the aircraft, the cockpit control placarded, and the maintenance recorded (in the airplane's logbooks, including a change to the Equipment List and the Weight and Balance information); or
  • deactivated and placarded "inoperative," with the pilot determining that the inoperative equipment does not constitute a hazard to the aircraft.

"Okay, then," my Baron student says, "we have to deactivate the annunciator and place a placard on the instrument panel stating the left alternator warning light is inoperative. Then we can fly."

"Well," I reply, "that may not be entirely true. There's one more place we need to look."

Remember "the airplane's Pilots Operating Handbook does not otherwise require the equipment be in working order" from FAR 91.213 (d)? Turns out that like many airplanes, the Beech Baron has a Kinds of Operations and Equipment list in Section II of the Pilots Operating Handbook. 91.213 (d) says "...a person may takeoff an aircraft in operations conducted under this part (FAR 91) with inoperative instruments and equipment without an approved Minimum Equipment List provided…the inoperative instruments and equipment are not...indicated as required...on the Kinds of Operations and Equipment List for the kind of flight operation being conducted...."

Translation: We do NOT have flexibility to placard equipment inoperative and continue flight operations, IF the inoperative equipment is listed as "required" on the POH Kinds of Operations and Equipment table.

In my student's Baron, the POH Kinds of Operations and Equipment List allows one of the alternator warning annunciators to be inoperative, so long as the alternator loadmeter for that engine is functioning and are monitored by the pilot. So the answer is YES. He CAN take off again with the malfunctioning alternator warning, if the associated alternator loadmeter continues to work. Pull out the annunciator's light bulb, install a placard on the panel, and fly.

The regulations refer to something called the Minimum Equipment List, often called the "MEL." An MEL is an airplane model- and operator- (registered owner or certificated carrier [charter or airline]) specific agreement between that operator and the FAA. The MEL lists the minimum items required to safely (read: legally) begin a flight. The MEL is thoroughly reviewed by the FAA and carries the force and effect of a Federal Air Regulation -- in effect it is a revision of the airworthiness sections of the Federal Air Regulations that applies only to that operator, flying that type of airplane.

Any inoperative item on an MEL calls for grounding the airplane if the MEL specifies that equipment be operable for a given type (i.e., VFR, IFR, night, revenue) of flight.

Note: There may be an option of placarding and disabling certain equipment for types of flight ONLY if that particular equipment outage, disabling/placarding procedure, and continued operation is spelled out in the MEL. The MEL is not transferable to other operators, or other types of airplanes.

ADVANTAGE OF THE MEL: If approved, an MEL may allow some operations that are not permitted normally, such as a day, VFR maintenance flight with that disabled alternator warning flight out if the associated loadmeter was also broken. All such contingencies must be anticipated and included, in writing, in the proposed MEL before approval.

DISADVANTAGE OF THE MEL: Like any special approval, much time, expense and effort is often required to complete the process of obtaining an MEL for your airplane.

Note: An oft-cited disadvantage is that the MEL is not transferable to a new owner/operator. In reality this isn't a problem; if ownership/operator status changes, the MEL is null and operation of the airplane simply reverts to 91.213 and/or the kinds of Operations and Equipment List from the POH.

If you find some instruments or installed equipment inoperative in an airplane you intend to fly, use this legal airworthiness decision tree:

  1. Is the equipment required for the type (DVFR, NVFR, IFR) of flight (FAR 91.205)? IF YES, GO TO STEP 5. IF NO, GO TO STEP 2.
  2. Does the aircraft's Pilots Operating Handbook contain a Kinds of Operations Equipment List in the Limitations section? IF YES GO TO STEP 3. IF NO GO TO STEP 4.
  3. Is the equipment required to be operable under the Kinds of Operations Equipment List in the Limitations section of the airplane's Pilot's Operating Handbook (FAR 91.213 (d))? IF YES, GO TO STEP 8. IF NO, GO TO STEP 4.
  4. Can the equipment be disabled and placarded as inoperative (FAR 91.213 (d))? IF YES, GO TO STEP 6. IF NO, GO TO STEP 5.
  5. Are you operating the airplane under an approved MEL, and does the MEL require the equipment to be operative for the type of flight (FAR 91.213 (a-c))? IF YES, GO TO STEP 8. IF NO, GO TO 6.
  6. Disable, placard and document as inoperative the affected equipment.
  7. Fly the airplane, paying special attention to back-up indicators or equipment that take the place of the failed equipment. Exit this checklist.
  8. Do not fly the airplane until the equipment has been repaired or replaced.

BOTTOM LINE: In an ideal world, we'd never fly an airplane if anything in it were broken. In reality, we need to evaluate the safety and operational impact of dealing with those minor break-downs common to any complex piece of machinery. The Federal Aviation Regulations and similar documents are designed to help us make these critical, life-threatening decisions. Make sure you know what your airplane needs to fly safely…and within the limits of the law.

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About This Author:
Tom Turner is a widely published author and regular forum speaker at EAA's Oshkosh/Airventure and American Bonanza Society. Tom holds an M.S. in Aviation Safety with an emphasis on pilot training methods and human factors. He has worked as lead instructor at FlightSafety International, developed and conducted flight test profiles for modified aircraft and authored three books including: Cockpit Resource Management: The Private Pilot's Guide and Instrument Flying Handbook (both from McGraw-Hill). His flight experience currently spans 3000 hours with approximately 1800 logged as an instructor. Tom's certificate currently shows ATP MEL with Commercial/Instrument privileges in SEL airplanes.
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