Maintenance Records

Jan. 26, 2006
An inspection program for a large or multi-turbine powered airplane or turbine-powered rotorcraft will generally consist of the following types of inspections: look-phase inspections and special inspections which Joe Hertzler describes in Part 2 of this article.

Part 1 of this story on what aircraft maintenance records are required for an aircraft owner/operator (14 CFR Part 91.417) appeared in the November/December 2005 issue which can be found in our article archives at

Inspection Status

14 CFR Part 91.417 (a)(2)(iv) The current inspection status of the aircraft, including the time since the last inspection required by the inspection program under which the aircraft and its appliances are maintained.

14 CFR Part 91.417 is applicable to all aircraft operating under Part 91. Therefore, it is here that we must discuss the difference in inspection requirements based on aircraft complexity. 14 CFR Part 91.409 contains two specific sections that should be more clearly defined.

91.409(a)(b)(c) and (d) refer to annual, 100-hour and progressive inspection programs and is directed toward smaller aircraft. The real distinction and separation line is found in 91.409(e). It applies specifically to “Large airplanes (12,500-pound max gross take- off weight, regardless of mode of power), turbojet multi-engine airplanes (regardless of weight class), turbo-propeller powered multi-engine airplanes (regardless of weight class), and turbine-powered rotor craft (regardless of number of engines or weight class),” Thus, every other type of aircraft falls under 91.409(a) through (d).

The significance here is that the inspection requirements for the larger more complex aircraft are no longer as simple as an annual inspection in scope and detail (Ref 14 CFR Part 43 Appendix D). The scope and detail of the inspection(s) required for these aircraft is that offered by the manufacturer of the airframe, engines, propellers, rotors, appliances, survival equipment, and emergency equipment, or a similar program that has been submitted to the FAA for evaluation and approval either by the owner of the aircraft (owner’s program) or an air carrier. A program that has been submitted by an air carrier and approved by the FAA for an identical aircraft model may be used by an operator under 14 CFR Part 91. In such cases, the air carrier who owns the inspection program must continue to operate an aircraft of the same make model that is subject to the same approved inspection program under their certificate thus keeping the program active (Ref 14 CFR Part 91.409(f)(1) and (2)).

Having gone through that detailed explanation, we can now see that the “current inspection status of the aircraft” can be a bit more complicated than we first thought. An inspection program for a large or multi-turbine powered airplane or turbine-powered rotorcraft will generally consist of the following types of inspections:

  • Look-phase inspections (“A” Check, Phase 2, 300-hour/12-month, etc.) — consists of several inspection tasks in several different areas of the aircraft due at the same frequency interval. The items contained in a look-phase inspection are generally listed on an inspection guide to help keep track of items as they are inspected. Don’t forget those look-phase inspections called out by the manufacturer of the engines, props, etc. They are also required as a part of a complete inspection
  • Special inspections — Where each specific inspection item is independent of other special inspection items. Special inspection items are not generally included on look-phase inspection guides. Special inspections are required at intervals other than look-phase inspection intervals, or derivatives thereof, for the aircraft and therefore don’t fit into the look-phase inspection cycle. Again, the manufacturers of the engines, propellers, etc., will likely have special inspections that must be accomplished in addition to those called out by the airframe manufacturer.

A list of required inspections for a large or multi- turbine powered aircraft includes many items and many different inspection intervals. Often, the special inspections are also based upon landings or cycles on an aircraft, again, reinforcing the need to track total cycles as well as total times.

In order to be able to provide the “current inspection status of an aircraft” required by the rule we need to be able to answer the following questions:

  • What inspection program has been selected for the aircraft?

  • What are the required look-phase inspections and special inspections for the airframe, engines, propellers, rotors, appliances, survival equipment, and emergency
  • When was the last time that each of the required inspections was accomplished?

  • When is the next time each item is required to be accomplished again?

Applicable Airworthiness Directives

14 CFR Part 91.417 (a)(2)(v) The current status of applicable airworthiness directives (AD) including, for each, the method of compliance, the AD number, and revision date. If the AD involves recurring action, the time and date when the next action is required.

The current status of applicable ADs is often interpreted to mean a separate list of all ADs accomplished including who complied with it, how it was complied with, and when it was complied with, etc. But the rule is really not any different than the one requiring a record of inspections or overhauls. Accurate and complete maintenance records will include proper documentation of AD compliance throughout the records as each AD is complied with. It is only practical however, to create a list of all applicable ADs and identify in that list, the information required by this rule:

  • The AD number

  • The revision or effective date of the AD (not the amendment number)

  • The method of compliance for the AD

  • If the AD requires recurring action, the time and/or cycles and date it will next be due.

As a matter of practice, maintenance providers should provide all of this information with each record of accomplishment of an AD to assist the owner/operator in meeting their record-keeping requirement.

Major Alterations (FAA Form 337)

14 CFR Part 91.417 (a)(2)(vi) Copies of the forms prescribed by §43.9(a) of this chapter for each major alteration to the airframe and currently installed engines, rotors, propellers, and appliances.

A quick scan of this rule can leave the wrong impression. At first glance it looks as though we need to have a record of all FAA Form 337s. But this rule is the one that makes a distinction between major repair and major alteration documentation retention requirements. Only FAA forms used to properly document major alterations are required to be retained and transferred with the aircraft (although the value of the aircraft can be greatly impacted and the salability crippled without all FAA Form 337s).

Major repairs must be documented in accordance with 14 CFR Part 43.9 as well, but when you look at Appendix B to Part 43 you will see that a repair station may, if they so choose, use a signed copy of its work order to approve for return to service major repairs so long as those repairs are accomplished in accordance with “a manual or specifications acceptable to the Administrator” (Ref 14 CFR Part 43 Appendix B (b)). We recommend that all FAA Form 337s completed for an aircraft be maintained in a separate three-ring binder. Often maintenance personnel need to refer to a 337 in order to answer maintenance questions. It is helpful to be able to put our hands on them quickly and not run the risk of losing them. One common practice is to place all FAA Form 337s in the weight and balance section of the aircraft flight manual. This also works well if all are placed there, but too many times we have seen them scattered all over the records.

So you can see, the requirement to permanently keep these “Category A” items, i.e. the current status of the aircraft, is a little more complex than it appears. A complete aircraft maintenance status tracking and reporting system is really the only practical solution for large or multi-turbine powered aircraft and turbine-powered rotorcraft. Such a tracking system should include all required inspections, all recommended overhauls, all airworthiness directives, all life-limited parts and the current total times and landing/cycles for the aircraft. The key is to be sure that each item listed in the status report is accurately supported by signed maintenance record entries contained throughout the maintenance logbooks.

Expiring Records — Category B

Now, let’s talk about items referred to in 14 CFR Part 91.417 (1). We will call them “Category B” items or expiring records.

14 CFR Part 91.417 (a)(1) reads as follows:

(1) Records of the maintenance, preventive maintenance, and alteration and records of the 100-hour, annual, progressive, and other required or approved inspections, as appropriate, for each aircraft (including the airframe) and each engine, propeller, rotor, and appliance of an aircraft. The records must include:

(i) A description (or reference to data acceptable to the Administrator) of the work performed; and
(ii) The date of completion of the work performed; and
(iii) The signature and certificate number of the person approving the aircraft for return to service.

A description of the work performed, date of completion, and signature of the person approving the work are all three mirrored from 14 CFR Part 43.9 which calls out the requirement for the maintenance person to document the maintenance performed. This correlation, although subtly, demonstrates the shared responsibility between maintenance personnel and the owner/operator.

Maintenance records that fall into Category B are required to be kept until the work is accomplished again or for a period of 12 months (Ref. 14 CFR Part 91.417 (b)(1)). This indicates that these records, if not superceded by new identical records within the first 12 months following approval for return to service, may be discarded. (Caution: Don’t discard those records.) But do understand what you are required to keep. Category B items include, maintenance performed (including major repairs), preventive maintenance performed, minor alteration records, and records of inspections. Looking at 91.417 (a)(1) you will notice reference to “100-hour, annual, and progressive inspections and other required or approved inspections.” This statement may seem to create a conflict in that the “inspection status” of the aircraft must be maintained permanently and transferred with the aircraft (Ref 14 CFR Part 91.417 (a)(2)(iv) and 91.417 (b)(2)). Well, for example, the 100-hour annual and progressive inspection records need not be retained when they have been superceded within the required 12 months. This does not alleviate the requirement to keep the current status of all inspections.

Next issue we will continue our topic with a discussion about the impact accurate maintenance records can have on the value of an aircraft and the regeneration of lost or stolen maintenance records.

About the Author

Joe Hertzler