Are they all there or do we need more?
By Joe Hertzler
The Logbooks – Is that all there is?
When it comes to aircraft logbooks, the format that they are set up 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. spells out 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. They reflect 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." Let’s discuss each type of record specifically addressed by the Regulation.
Total time-14 CFR Part 91.417 (a)(2)(i)
Having record of the total time in service of the airframe, each engine, and each propeller and each rotor simply involves keeping track of time accumulation. "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 will be several different total times to monitor and tally up each time. 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 recommend to record all applicable total times and cycles in every maintenance record entry whenever possible.
Life limited parts-14 CFR Part 91.417 (a)(2)(ii)
Life limited parts 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.
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 of life limited parts we need to know the following questions:
1. Which parts are life limited?
2. What are their serial numbers?
3. What are their life limits
4. How much of the limit is left?
Additionally, some life limited parts must be replaced based not upon total time in service, but upon total cycles in service. When the life limited parts 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 demonstrate that the part is not past the limit. The situation then mandates tracking of landings and cycles in order to demonstrate compliance.
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