Inoperative Equipment & Airworthiness

“ATOMATOFLAMES!!!” Students’ (incorrect) response to any INOP equipment question

A dragonfly that flew straight into my stall indicator on landing after an aerobatic flight. Could I have flown without it if this had happened before the flight?

In my career as a flight instructor and stage check instructor, I have never encountered a more tragic topic than inoperative equipment and airworthiness. I regularly ask my students and my stage check candidates questions concerning airworthiness and inoperative equipment, and I realized that it’s a heavily misunderstood topic. Hopefully this article sheds some light on when you can or cannot work.

The Big Picture of Flying with Broken Stuff

The high-level requirement that dictates airworthiness and inoperative equipment is the following:

“Everything must work”.

If something does not work or is broken, then you have three choices:

1. Fix it.

2. Remove it.

3. Defer it.

Option (1) will probably delay your flight. Whether it’s replacing a light bulb or tightening a panel, it will obviously take time. Option 1 is my favorite, cause airplanes are supposed to be in great shape all the time. Option (2) will definitely delay your flight. It sucks, I know, but safety is safety. Hopefully your ruined day will prevent future headaches. Maybe that will make you feel better. Option (3) is the often “necessary” option if you have a mission to complete. But there are limitations on deferring it.

You can only defer it if, and only if:

1. It is not required by regulation or guidance.

2. You, the PIC, believe it to be necessary for the flight.

There are regulations that specify what is required for flight, and we’ll talk about that later in the article. If you only care about that, choose scroll to the heading “Flying with INOP stuff”.

To defer it, your inoperative equipment, you must:

1. disconnect power to it

2. placard it as INOP

3. have a MX record entry stating that it’s deferred.

By the way, deferred means that “you will fix it at a later time”. Reasonableness is important here, cause some things can be fixed at the 100 hour, others just need to wait for MX personnel to be present, and others can be fixed at the annual. However, the intent must be to fix it. Deferring doesn’t mean that you will just continue to fly “with it broken” indefinitely. This is very important. This argument does not apply to everything. If you are missing a maintenance panel, you can’t just placard it INOP, since it’s not “equipment” but rather a “piece of the airplane”. Would you fly with “a piece of the airplane” missing? Ahah. No.

If you wish to remove it (that was option 2)

1. weight and balance needs to be adjusted by someone who is certified

2. a maintenance record must be entered.

Ok, now that you get the high level stuff, let’s dive into more nerdy concepts.

Airworthiness

Airworthiness is granted by the Federal Aviation Administration (FAA) when all the conditions specified in the Type Certificate (TC) are complied with. This is public information (the TC, I mean) and searchable on the FAA website.

Airworthiness is dependent on conformity. This is a certification term that indicates that the airplane is configured per the Type Certification Data Sheet (TCDS). My friend and colleague John described it best as “the airplane must look just like when it sat in the showroom”. Sure, the paint job is probably not identical, but the configuration must be the same. Each item in the TCDS is included in the certification of the aircraft. Certification is the key term, here. The airplane was certified by the FAA with the configuration specified in the TCDS. If you fly it with something “missing” from the TCDS, you are flying in unknown territory (and illegal, too). Let’s say a panel is missing. Well, that may affect stall and spin characteristics, and who knows… maybe the airplane now becomes unrecoverable. So, don’t fly it.

• The owner/operator is responsible to keep the airplane conformed to the TCDS.

• The Pilot in Command (PIC) has the responsibility of determining if the aircraft is in a condition for safe flight. This is true even if the airplane is airworthy! This is an awesome responsibility. Learn more about PIC responsibilities here. We can narrow this responsibility down in three aspects:

When asked if the airplane is airworthy (say by a DPE during your checkride, for example), two conditions must be met:

1. Maintenance, preventive maintenance, and alterations must be performed according to the FARs

2. The aircraft must be registered in the U.S.

The average pilot is not an aerospace engineer or an airworthiness expert. So what things can a PIC look at? Well, maintenance and registration paperwork is easily found in the aircraft’s records. So let’s see what maintenance requirements exist under each regulation.

Maintenance Inspections

WHO can do maintenance on an airplane is specified under 14 CFR Part 45.

HOW the maintenance is to be completed is specified under 14 CFR Part 45.

WHAT maintenance is to be completed is specified under 14 CFR Part 91.

WHICH parts can be used for maintenance is specified under 14 CFR Part 21.

As PIC, you probably have little to no awareness on The WHO, HOW, and WHICH. You are however very capable of checking the WHAT.

So what maintenance should be completed? this is the answer to your DPE’s question on whether the airplane is airworthy.

1. AV1ATE: One of your most favorite acronyms

   1. Annual (91.409)

      1. Once every 12 months

   2. VOR Checks (91.171)

      1. In the preceding 30 days

      2. For IFR flight, only

   3. 100 hr inspection (91.409)

      1. If for hire or flight instruction

   4. Altimeter (plumbing on static system)

      1. In the preceding 24 calendar months

      2. For IFR flight, only

   5. Transponder (91.413)

      1. In the preceding 24 calendar months

   6. ELT (91.207)

      1. In the preceding 12 calendar months

      2. Batteries replaced/recharged if used for more than 1 cumulative hour or 50% of useful life is expired.

2. Airworthiness Directives (14 CFR Part 39)

   1. These are inspections/replacements that the FAA determined must be done in order to keep the airplane safe. If not complied with, the airplane is not airworthy.

3. GPS Current DB

   1. If flying IFR (there are exceptions, but that’s a longer conversation).

The quality of the inspections or maintenance actions is very important. The FAA dictates under 14 CFR 43.13 that the work must be done to bring the airplane back to “at least equal to its original or properly altered condition (with regard to aerodynamic function, structural strength, resistance to vibration and deterioration, and other qualities affecting airworthiness”. So “good as new”. The service limits are specified in the TCDS, convenient, eh?

Flying with INOP Stuff

As discussed at the beginning of this article, you can “defer” a repair action if the item is not:

1. Required by the regulations or guidance

2. The PIC (that’s you) determines it is not required for the flight (yes, subjective, but be conservative).

You will find a lot of diagrams and flowcharts on determining if you can fly with something broken. Well, here is my thought process.

1. CONFORMITY - Is the airplane conformed without it? Is it part of the TCDS? Some things are obvious, other things are not. So you may have to research it. Having a competent mechanic may help you to figure it out, too.

2. AIRWORTHINESS DIRECTIVE - Is the broken thing required by an airworthiness directive? Let’s say an AD requires the addition of an electrical fuel pump for a specific engine. Well, if it’s required, you can’t fly if it’s broken! This really involves you “knowing your airplane”.

3. AIRPLANE FLYING MANUAL (AFM) - Does the AFM say anything about that item? Is there a limitation or required equipment section for certain operations? The AFM is certified by the FAA, too (if your airplane has one, this is more of a big airplane thing), so you again, you have to “know your airplane”.

4. INOPERATIVE INSTRUMENTS AND EQUIPMENT (14 CFR 91.213) - This regulation goes down a list of things to look at and verify your broken item is not required.

   1. Minimum Equipment List (MEL). Does your airplane have an MEL? If yes, it will dictate what items are needed. It’s rather comprehensive, but will not list every possible screw on the airplane. Again, consider “conformity”. The MEL is specific to an airplane model, and an MMEL (Master MEL) can apply to a family of aircraft. This is usually a separate document (massive one, usually) and not within your average POH. It’s part of the aircraft’s documentation and often subject to updates by the manufacturer.

   2. ATOMATOFLAMES!!! Here, you have it. If the airplane does not have an MEL, then 91.205 applies. Now, I don’t have 91.205 memorized, and I do not require my students to learn it, either. They need to know the process and how to reference it. Remember, again, that an MEL overrides 91.205. Beware also that there are other regulations that supplement or override 91.205. Lights is a great example. 91.209 requires all lights to be functioning, if installed. So you have to go down a rabbit hole to figure out what is and isn’t required based on supplemental type certificates and more.

   3. Kinds of Operations Equipment List (KOEL). This is a form of “limitations” found in your airplane’s manual. It specifies for specific types of operations (day, night, VFR, IFR), what equipment you have, and what you need to be operative.

5. REQUIRED OR UNSAFE FOR FLIGHT. Do I need my broken thing to execute the flight? For example, if my transponder is broken, what airspace can I fly or not fly in? If I’m going to a very random location and GPS will help me get there, do I need it? Again, you’re PIC. Be safe and be good.

If the answer is “no” to all of these, then you can go fly. As a reminder, if you end up flying with something INOP, you still need to comply with 91.213(d)(3) which says the following:

1. Item was removed

   1. Re-calculated weight and balance

   2. Maintenance record

2. Item was not removed

   1. Item must be deactivated (not power going to it)

   2. Maintenance record if deactivation requires maintenance

Please be conservative with inoperative equipment and consider carefully your flight profile. If you’re heading at night with an inoperative landing night to an unfamiliar unlit field, that can be very unsafe, even if not required by the regulations. So deferring is a slippery slope that needs to be avoided. And you’re PIC. So take the role seriously.