Baker's Dozen: The addition to Part 43

The first three months of every year I travel around the country giving IA seminars to explain and defend the Federal Aviation Regulations. I always ask this question at the beginning of my talks on Part 43: "Mechanics do you think your industry is over regulated?" After checking the back of the room to see if the local FSDO inspector is still there, the brave always reply, although somewhat apprehensive, that yes they are.

Then I ask the question, "Since Part 43 is the part that covers maintenance, preventive maintenance, rebuilding and alteration, and applies to more than 185,000 U.S. registered aircraft, just how many sections or individual rules are in Part 43?"

This usually throws them, because no one counts the number of rules in a Part except DC bureaucrats like myself. So I get answers that Part 43 has one to 100 different kinds of rules. When I tell them that there are only 12 rules and six appendixes in Part 43, all of a sudden the regulations do not appear to be bigger than they are, the door to learning is open, and I can go to work.

On April 15, 2002, I'll have to change my presentation to reflect the fact that a new rule will be added to Part 43. Instead of 12 rules we will have 13, or a baker's dozen. This new rule, section 43.10 will address the safe disposition of life-limited parts by persons performing maintenance on type-certificated products.

How did it come to be?

Despite popular opinion, the FAA does not enter into rulemaking with a willing heart. This is because rulemaking is a messy business, heavy with compromise and frustration. Even in the best of times, with FAA senior management support and a lot of industry input, the final rule always seems to have something in it which no one is happy with. So, battered and bashed, we bureaucrats in Washington, must be driven, not led to the rulemaking process.

There are three basic kinds of drivers that pressure the FAA to promulgate rulemaking. The most common driver for a new rule is one that satisfies a safety concern such as a new Airworthiness Directive or the recent rule for strengthening cockpit doors on aircraft.

The second driver for rulemaking is a rule requested by industry or private individuals. An example of this is the Sport Pilot rule.

The third driver for rulemaking is less common than the first two, but in many ways the proposed rule is 100 percent guaranteed to happen because the driver for the new rule is a law passed by Congress.

In the case of creating section 43.10 its driver was the Wendell H. Ford Investment and Reform Act for the 21st Century (Public Law 106-181) which required the FAA Administrator to conduct rulemaking proceedings to require the safe disposition of life-limited parts removed from aircraft. You can get an electronic copy of the rule at

The reason behind the law requiring the FAA to ensure how life-limited parts are properly disposed came from the FAA in its investigation of Suspected Unapproved Parts. FAA Inspectors found numerous findings of parts that had reached or exceeded their life limit and were scrapped, but were rebuilt, re-marked, and installed back on aircraft.

What does the rule say?

Section 43.10 has four major paragraphs that are identified alphabetically.

Section 43.10 (a): Definitions. This paragraph defines two words used in the section. The words are: Life-limited part is any part for which a mandatory replacement limit is specified in the type design, the instructions for continued airworthiness, or in the maintenance manual; Life-status is defined as meaning the accumulated cycles, hours, or any other mandatory replacement limit of a life-limited part.

Section 43.10 (b): Temporary removal of parts from a type-certificated product. This rule deals with a life-limited part that is temporarily removed from an aircraft and then reinstalled on the same aircraft for the purpose of performing maintenance. Like doing a hot section inspection on a PT-6. This paragraph basically says no recording or marking has to be done to the part if the life status has not been changed, the part goes back on the same aircraft, and the aircraft does not fly while the life-limited part is in maintenance.

Section 43.10 (c):
Deals with the disposition of parts removed from type-certificated products. It says a life-limited part removed from a TC aircraft or product must be controlled so the part cannot be used again if the part's life-limit has been reached or the part is going to be installed on another TC product. Acceptable methods of controlling the part while it is off the aircraft include:

1. A record-keeping system: This should substantiate the part number, serial number, and current life-status of the part. Each time the part is removed from a type-certificated product, the record must be updated with the current life status. This record-keeping system may include electronic, paper, or other means of record keeping.

2. Tag or record attached to the part: A tag or record may be attached to the part. The tag or record must identify the part number, serial number, and current life-status of the part. Each time the part is removed from a TC product a new tag or record must be created or the existing tag or record must be updated with the current life status.

3. Non-permanent marking. The part may be legibly marked using a non-permanent method showing its current life-status. You can use methods such as a non-permanent marking pen, label maker, stick-on labels, etc. As before, the marking must be updated with the current life-status of the part each time it is removed. If you use non-permanent markers, the part must be marked in accordance with section 45.16 Marking of life-limited parts. This companion rule to section 43.10 says the maker of a life-limited part must provide marking instructions or state the part cannot be practicably marked without compromising its integrity. The manufacturers can provide these marking instructions in the maintenance manual or instructions for continued airworthiness. I suspect it will take some time for the manufacturers to get these marking instructions in their manuals so my advice is to tag the part.

4. Permanent markings. The part may be marked in accordance with section 45.16 using a permanent means such as electric pencil, or die letters, etc. Again, the marking must be updated with the current life-status of the part each time it is removed. This might get a little tricky, especially if the area for marking is small or the part is installed on several aircraft. So I still favor the tag method.

5. Segregation. A part that has reached its life limits must be physically stored away from the rest of the parts currently eligible for installation. While it is in storage the organization must have a record of the part's serial and part number and current life status.

6. Mutilation. A life-limited part that has come to the end of its trail may be mutilated. Now before you send the part to the scrap yard you need to get permission from the owner to destroy it. If he wants the part back, give it to him, but make sure on the customer's work order that you have identified the part by part number and serial number and you declared the part as unairworthy and should be scrapped. Methods of mutilation include cutting the part in half, welding ID marks on it, crushing, etc. The mutilation must render the part incapable of being repaired or reworked so it looks airworthy.

7. Other methods: This paragraph allows some wiggle room in the rule by allowing any other method to control a life-limited part, to be approved or accepted by the FAA. So in 2015 when parts can be routinely marked with bar codes or laser beams the rule does not have to be re-written.

Section 43.10 (d): Transfer of life-limited parts. When a mechanic transfers a life-limited part from one TC aircraft or product to another, the part must be tagged or marked with the appropriate information to comply.

So we covered the new rule, and there wasn't anything in it that seemed unreasonable. In fact because of the Suspected Unapproved Parts problems that industry suffered through in the '90s, most repair stations, and air carriers/operators already must comply with these life-limited parts handling procedures in accordance with their required manuals. It's the Part 91 mechanics and IAs who might be caught napping by lucky number 13 because they didn't properly control or dispose of the life-limited part.