Around The Hangar
Maintenance Records, Part 2
What do I need to keep?
By Joe Hertzler
This is the second of a three-part series discussing maintenance records and the regulations that require us to record the maintenance we have performed.
The first discussed the role of maintenance personnel and organizations in the recording of work accomplished. Here we will outline what records are required for an aircraft owner/operator and dig deep into the details of each paragraph in the regulation — 14 CFR Part 91.417(a)(1)&(2).
The logbooks: Is that all there is?
When it comes to aircraft logbooks, the format that they are kept in can vary drastically from aircraft to aircraft. Regardless of the format or quantity of logbooks and maintenance records, the question arises "What content is required by regulation?"
14 CFR Part 91.417 describes what maintenance records are required and how long those records must be kept by the owner/operator. For simplification, maintenance records called out in this rule can be divided into two categories — permanent records and expiring records.
Permanent records are those maintenance records that must be kept and maintained for the aircraft indefinitely and provided to a new owner when the aircraft is sold. These records translate into the current "status" of the aircraft. 14 CFR Part 91.417 (a)(2) lists the permanent records that must be "retained and transferred with the aircraft at the time the aircraft is sold."
Having a record of the total time in service of the airframe, each engine, propeller, and rotor simply involves keeping track of time accumulation (14 CFR Part 91.417 (a)(2)(i)). "Time in service" essentially means; from the time the tires on the landing gear leave the ground to the time the tires touch back down. This can get tricky when engines, propellers, and rotors are replaced with new or time continued components. After carrying over the correct times, there can be several different total times (airframe, engine, propeller/rotor) to monitor and tally up after each flight. It is the responsibility of the owner/operator of the aircraft to know and provide the aircraft total time to the FAA and to maintenance personnel when required. Although maintenance record entries only require total time references when an inspection is accomplished (Ref 14 CFR 43.11), it is highly recommended to record all applicable total times and cycles in every maintenance record entry when possible.
Life limited parts
Life limited parts (14 CFR Part 91.417 (a)(2)(ii)) are those parts that have received a specific life limit from an approved FAA document for that aircraft. Some examples of FAA-approved documents are the Type Certificate Data Sheets (TCDS), Approved Airplane Flight Manual, the FAA Approved Airworthiness Limitations Section of the aircraft maintenance manual, and Airworthiness Directives (ADs).
With the exception of life limited parts called out by ADs, life limits generally begin with the Type Certificate. The Type Certificate will contain either specific reference to parts numbers that are required to be replaced at a specific time or refer us to a document that contains such information. To determine what parts are "life limited" for your aircraft, it is usually best to start with the Type Certificate Data Sheet and follow the road signs from there.
The regulation refers to the "current status" of life limited parts. To know the current status we need to know the following:
- Which parts are life limited?
- What are their serial numbers?
- What are their life limits?
- How much of the life limit is left?
Life limited parts can be limited by hours, cycle, calendar frequencies, or any combination thereof. When the limitation is based upon total time in service or a calendar frequency, it’s usually pretty straightforward. But when life limits are based upon total cycles in service we sometimes get into trouble. When the replacement requirement calls out replacement of a part at a total cycle count of XYZ, and we don’t know the total cycle count, we cannot prove that the part is not past the limit and the part must be replaced (costly). We recommend the tracking of landings and cycles even if your aircraft doesn’t currently have any cycle limited parts. The manufacturer can introduce cycle limits anytime during the life of the aircraft.
Time since overhaul
Overhaul times are generally called out in maintenance manuals and service information. The maintenance manual usually lists the items that the manufacturer requires to be overhauled. The rule requires that we be able to show the time since last overhaul for those items (14 CFR Part 91.417 (a)(2)(iii)).
This rule does not mandate the overhaul of such items, just the recording of the time since last overhaul. For operations conducted under 14 CFR Part 91, overhaul is not a mandatory requirement as long as the item continues to pass required inspection criteria, although it is usually very desirable to perform overhauls at the recommended intervals. Delay in overhauls can cost more in the long run due to worn parts and sub components. Also, be aware of your insurance requirements. Some policies require all manufacturer recommendations to be followed in order for the aircraft to be covered.
The current inspection status (14 CFR Part 91.417 (a)(2)(iv)) for your aircraft must be properly documented as well. 14 CFR Part 91 contains aircraft inspection requirements. The requirements can vary greatly depending on aircraft classification. They can range from annual inspections on GA aircraft to look-phase inspections on the larger more complex aircraft. Special inspections that are tracked by landings or cycles may also need to be recorded.
In order to be able to provide the current inspection status of an aircraft required by the rule, the following should be answered:
- What inspection program has been selected for the aircraft?
- What are the required look-phase inspections and special inspections for my airframe, engines, propellers, rotors, appliances, survival equipment, and emergency equipment installed on my aircraft?
- When was the last time that each of the required inspections was accomplished?
- When is the next time each items is required to be accomplished again?
Accurate and complete maintenance records will include proper documentation of AD compliance throughout the records as each AD is complied with (14 CFR Part 91.417 (a)(2)(v)). 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 topic of the AD (optional), the revision or effective date of the AD (not the amendment number), the method of compliance for the AD, and if the AD requires recurring action, the time and/or cycles and date it will next be due.
This rule requires that only FAA Form 337s that document major alterations (14 CFR Part 91.417(a)(2)(vi)) need to be retained permanently and transferred with the aircraft. However, the value of the aircraft can be greatly impacted without all FAA Form 337s. It is a good idea to keep all 337s including those for major repairs. This practice can also assist maintenance personnel who may need to refer to a 337 in order to answer maintenance questions.
Now, let’s talk about maintenance record items that fall into the category of expiring records (14 CFR Part 91.417 (a)(1)).
(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. (Incidentally, this requirement mirrors the requirement to document maintenance found in 14 CFR Part 43 for maintenance personnel.)
Maintenance records that fall into this category are required to be retained until the work is accomplished again or for a period of 12 months (Ref 14 CFR Part 91.417 (b)(1)). Thus, these records, if not superseded by new, identical, records within the first 12 months following approval for return to service, may be discarded. (Caution: Don’t discard those records.) Expiring records include, maintenance performed (including major repairs), preventive maintenance performed, minor alteration records, and records of inspections. Although inspection records (100-hour, annual, and progressive) do not need to be retained when they have been superseded within the required 12 months, this doesn’t alleviate the requirement to keep the current status of inspections.
In summary, although not required, keep all maintenance records and keep them organized in a logical order. Organized and well-documented maintenance will only help your operation by maintaining aircraft value, eliminating duplicate work, and simplifying the research process for those who need to find things in your records. Next issue we will wrap up our maintenance records topic with a discussion about the impact of accurate maintenance records on the value of the aircraft and the re-generation of lost or stolen maintenance records.
Joe Hertzler is the president of AVTRAK Inc., an Aurora, Colorado-based company. He is an A&P mechanic with Inspection Authorization and also a private pilot.