US. Department of Transportation
							Advisory Circular

Subject: MAINTENANCE RECORDS
						Date:		6/8/98		AC No: 43-9C
					Initiated by:	AFS-340	Change:

1. PURPOSE. This advisory circular (AC) describes methods, procedures and practices that have been determined to be acceptable means of showing compliance with the general aviation maintenance record making and record keeping requirements of Title 14 of the Code of Federal Regulations (14 CFR) parts 43 and 91. This material is not mandatory, nor is it regulatory and acknowledges that the Federal Aviation Administration (FAA) will consider other methods that may be presented. It is issued for guidance purposes and outlines several methods of compliance with the regulations.

NOTE:	The information in this AC does not apply to air carrier maintenance 
		records made and retained in accordance with 14 CFR part 121.

2. CANCELLATION. AC 43-9B, Maintenance Records, dated January 9, 1984, is canceled. 

3. RELATED REGULATIONS. 14 CFR parts 1, 43, 91, and 145.

4. DISCUSSION. The Code of Federal Regulations state that a U.S. standard airworthiness certificate is effective until it is surrendered, suspended, revoked, or a termination date is otherwise established by the Administrator. In addition to those terms, a U.S. standard airworthiness certificate is effective only as long as the maintenance, preventive maintenance, and alterations are performed in accordance with parts 43 and 91, and the aircraft are registered in the United States. These terms and conditions are further restated, in block 6, on the front of FAA Form 8100-2, Standard Airworthiness Certificate. Qualified persons, who perform the maintenance, preventive maintenance and alterations, shall make a record entry of this accomplishment, thus maintaining the validity of the certificate of airworthiness. Adequate aircraft records provide tangible evidence that the aircraft complies with the appropriate airworthiness requirements. In accordance with the terms and conditions listed in block 6 of the Standard Airworthiness Certificate, insufficient or non-existent aircraft records may render that standard airworthiness certificate invalid.

5.	MAINTENANCE RECORD REQUIREMENTS.

  a.	Responsibilities. 14 CFR part 91, section 91.417 states that an aircraft owner/operator shall keep and maintain aircraft maintenance records. 14 CFR part 43, sections 43.9 and 43.11 state that maintenance personnel, however, are required to make the record entries.

  b.	Maintenance Records That Are to Be Retained.  Section 91.405 requires each owner or operator to ensure that maintenance personnel make appropriate entries in the maintenance records to indicate that the aircraft has been approved for return to service. Section 91.417(a) sets forth the content requirements and retention requirements for maintenance records. Maintenance records may be kept in any format that provides record continuity; includes required contents; lends itself to the addition of new entries; provides for signature entry; and, is intelligible. Section 91.417(b) requires records of maintenance, alterations, and required or approved inspections to be retained until the work is repeated, superseded by other work, or for one year. It also requires the records, specified in section 91.417(a)(2), to be retained and transferred with the aircraft at the time of sale.

NOTE:	Section 91.417(a) contains an exception regarding work accomplished in accordance with section 91.411. This does not exclude the making of entries for this work, but applies to the retention period of the records for work done in accordance with this section. The exclusion is necessary since the retention period of one year is inconsistent with the 24-month interval of test and inspection specified in section 91.411. Entries for work done per this section are to be retained for 24 months or until the work is repeated or superseded.

  c.	Section 91.417(a)(1). Requires a record of maintenance, for each aircraft (including the airframe) and each engine, propeller, rotor, and appliance of an aircraft. This does not require separate or individual records for each of these items. It does require the information specified in sections 91.417(a)(1) through 91.417(a)(2)(vi) to be kept for each item as appropriate. As a practical matter, many owners and operators find it advantageous to keep separate or individual records since it facilitates transfer of the record with the item when ownership changes. Section 91.417(a)(1) has no counterpart in section 43.9 or section 43.11.

  d.	Section 91.417(a)(1)(i). Requires the maintenance record entry to include "a description of the work performed." The description should be in sufficient detail to permit a person unfamiliar with the work to understand what was done, and the methods and procedures used in doing it. When the work is extensive, this results in a voluminous record. To provide for this contingency, the rule permits reference to technical data acceptable to the Administrator in lieu of making the detailed entry. Manufacturer's manuals, service letters, bulletins, work orders, FAA AC's, and others, which accurately describe what was done, or how it was done, may be referenced. Except for the documents mentioned, which are in common usage, referenced documents are to be made a part of the maintenance records and retained in accordance with section 91.417(b).

NOTE:	Certificated repair stations frequently work on components shipped to them without the maintenance records. To provide for this situation, repair stations should supply owners and operators with copies of work orders written for the work, in lieu of maintenance record entries. The work order copy must include the information, required by section 91.417(a)(1) through section 91.417(a)(1)(iii), be made a part of the maintenance record, and retained per section 91.417(b). This procedure is not the same as that for maintenance releases discussed in paragraph 16, and it may not be used when maintenance records are available. Section 91.417(a)(1)(i) is identical to its counterpart, section 43.9(a)(1), which imposes the same requirements on maintenance personnel.

  e.	Section 91.417(a)(1)(ii). Is identical to section 43.9(a)(2) and requires entries to contain the date the work was completed. This is normally the date upon which the work is approved for return to service. However, when work is accomplished by one person and approved for return to service by another, the dates may differ. Two signatures may also appear under this circumstance; however, a single entry in accordance with section 43.9(a)(3) is acceptable.

  f.	Section 91.417(a)(1)(iii). Differs slightly from section 43.9(a)(4) in that it requires the entry to indicate only the signature and certificate number of the person approving the work for return to service, and does not require the type of certificate being exercised to be indicated as does section 43.9(a)(4). This is a new requirement of section 43.9(a)(4), which assists owners and operators in meeting their responsibilities. Maintenance personnel may indicate the type of certificate exercised by using airframe (A), powerplant (P), airframe & powerplant (A&P), inspection authorization (IA), or certiflicated repair station (CRS).

  g.	Section 91.417(a)(2). Requires six items to be made a part of the maintenance record and maintained as such. Section 43.9 does not require maintenance personnel to enter these items. Section 43.11 requires some of them to be part of entries made for inspections, but they are all the responsibility of the owner or operator. The six items are discussed as follows:
	(1)	Section 91.417(a)(2)(i). Requires a record of total time-in-service to be kept for the airframe, each engine, and each propeller. Part 1, section 1.1, Definitions, defines time in service, with respect to maintenance time records, as that time from the moment an aircraft leaves the surface of the earth until it touches down at the next point of landing. Section 43.9 does not require this to be part of the entries for maintenance, preventive maintenance, rebuilding, or alterations. However, section 43.11 requires maintenance personnel to make it a part of the entries for inspections made under parts 91,125, and time-in-service in all entries.

		(a)	Some circumstances impact the owner's or operator's ability to comply with section 91.417(a)(2)(i). For example, in the case of rebuilt engines, the owner or operator would not have a way of knowing the total time-in-service, since section 91.421 permits the maintenance record to be discontinued and the engine time to be started at zero. In this case, the maintenance record and time-in-service, subsequent to the rebuild, comprise a satisfactory record.

		(b)	Many components, presently in-service, were put into service before the requirements to keep maintenance records on them. Propellers are probably foremost in this group. In these instances, practicable procedures for compliance with the record requirements must be used. For example, total time-in-service may be derived using the procedures described in paragraph 12; or if records prior to the regulatory requirements are just not available from any source, time-in-service may be kept since last complete overhaul. Neither of these procedures is acceptable when life-limited parts status is involved or when airworthiness directive (AD) compliance is a factor. Only the actual record since new may be used in these instances.

		(c)	Sometimes engines are assembled from modules (turbojet and some turbopropeller engines) and a true total time-in-service for the total engine is not kept. If owners and operators wish to take advantage of this modular design, then total time-in-service and a maintenance record for each module is to be maintained. The maintenance records specified in section 91.417(a)(2) are to be kept with the module.

	(2)	Section 91.417(a)(2)(ii). Requires the current status of life-limited parts to be part of the maintenance record. If total time-in-service of the aircraft, engine, propeller, etc., is entered in the record when a life-limited part is installed and the time-in-service of the life-limited part is included, the normal record of time-in-service automatically meets this requirement.

	(3)	Section 91.417(a)(2)(iii). Requires the maintenance record to indicate the time since last overhaul of all items installed on the aircraft that are required to be overhauled on a specified time basis. The explanation in paragraph 5g (2) also applies to this requirement.

	(4)	Section 91.417(a)(2)(iv). Deals with the current inspection status and requires it to be reflected in the maintenance record. Again, the explanation in paragraph 5g (2) is appropriate even though section 43.11 (a)(2) requires maintenance persons to determine time-in-service of the item being inspected and to include it as part of the inspection entry.

	(5)	Section 91.417(a)(2)(v). Requires the current status of applicable AD's to be a part of the maintenance record. The record is to include, at minimum, the method used to comply with the AD, the AD number, and revision date; and if the AD has requirements for recurring action, the time-in-service and the date when that action is required. When AD's are accomplished, maintenance persons are required to include the items specified in section 43.9(a)(2), (3), and (4) in addition to those required by section 91.417(a)(2)(v). An example of a maintenance record format for AD compliance is contained in Appendix 1.

	(6)	Section 91.417(a)(2)(vi). In the past, the owner or operator has been permitted to maintain a list of current major alterations to the airframe, engine(s), propeller(s), rotor(s), or appliances. This procedure did not produce a record of value to the owner/operator or to maintenance persons in determining the continued airworthiness of the alteration since such a record was not sufficient detail. This section of the rule has now been changed. It now prescribes that copies of FAA Form 337, issued for the alteration, be made a part of the maintenance record.

6. PREVENTIVE MAINTENANCE.

  a.	Preventive maintenance is defined in part 1, section 1.1. Part 43, appendix A, paragraph (c) lists those items which a pilot may accomplish under section 43.3(g). Section 43.7 authorizes appropriately rated repair stations and mechanics, and persons holding at least a private pilot certificate to approve an aircraft for return to service after they have performed preventive maintenance. All of these persons must record preventive maintenance accomplished in accordance with the requirements of section 43.9. AC 43-12, Preventive Maintenance, current edition, contains further information on this subject.

  b.	The type of certificate exercised when maintenance or preventive maintenance is accomplished must be indicated in the maintenance record. Pilots may use private pilot (PP), commercial pilot (CP), or air transport pilot (ATP) to indicate private, commercial, or airline transport pilot certificate, respectively, in approving preventive maintenance for return to service. Pilots are not authorized by section 43.3(g) to perform preventive maintenance on aircraft when they are operated under part 121,127, 129, or 135. Pilots may only approve for return to service preventive maintenance that they themselves have accomplished.

7. REBUILT ENGINE MAINTENANCE RECORDS.

  a.	Section 91.421 provides that zero time may be granted to an engine that has been rebuilt by a manufacturer or an agency approved by the manufacturer. When this is done, the owner/operator may use a new maintenance record without regard to previous operating history.

  b.	The manufacturer or an agency approved by the manufacturer that rebuilds and grants zero time to an engine is required by section 91.421 to provide a signed statement containing: 1) the date the engine was rebuilt; 2) each change made, as required by an AD; and 3) each change made in compliance with service bulletins, when the service bulletin specifically requests an entry to be made.

  c.	Section 43.2(b) prohibits the use of the term rebuilt in describing work accomplished in required maintenance records or forms unless the component worked on has had specific work functions accomplished. These functions are listed in section 43.2(b) and, except for testing requirements, are the same as those set forth in section 91.421 (c). When terms such as remanufactured, reconditioned, or other terms coined by various aviation enterprises are used in maintenance records, owners and operators cannot assume that the functions outlined in section 43.2(b) have been done.

8. RECORDING TACHOMETERS.

  a.	Time-in-service recording devices sense such things as electrical power on, oil pressure, wheels on the ground, etc.-, and from these conditions provide an indication of time-in-service. With the exception of those that sense aircraft lift-off and touchdown, the indications are approximate.

  b.	Some owners and operators mistakenly believe these devices may be used in lieu of keeping time-in-service in the maintenance record. While they are of great assistance in arriving at the time-in-service, such instruments, alone, do not meet the requirements of section 91.417. For example, when the device fails and requires change, it is necessary to enter time-in-service and the instrument reading at the change. Otherwise, record continuity is lost.

9. MAINTENANCE RECORDS FOR AD COMPLIANCE. This subject is covered in AC 39-7, Airworthiness Directives for General Aviation Aircraft, current edition. A separate AD record may be kept for the airframe and each engine, propeller, rotor, and appliance, but is not required. This would facilitate record searches when inspection is needed, and when an engine, propeller, rotor, or appliance is removed, the record may be transferred with it. Such records may also be used as a schedule for recurring inspections. The format, shown in Appendix 1, is a suggested one, and adherence is not mandatory. Owners should be aware that they may be responsible for non-compliance with AD's when their aircraft are leased to foreign operators. They should, therefore, ensure that leases should be drafted to deal with this subject.

10.	MAINTENANCE RECORDS FOR REQUIRED INSPECTIONS.

  a.	Section 43.11 contains the requirements for inspection entries. While these requirements are imposed on maintenance personnel, owners and operators should become familiar with them in order to meet their responsibilities under section 91.405.

  b.	The maintenance record requirements of section 43.11 apply to the 100-hour, annual, and progressive inspections under part 91; inspection programs under parts 91 and 125; approved airplane inspection programs under part 135; and the 100-hour and annual inspections under section 135.411 (a)(1).

  c.	Appropriately rated mechanics are authorized to conduct these inspections and make the required entries. Particular attention should be given to section 43.1 l(a)(7) in that it now requires a more specific statement than previously required under section 43.9. The entry, in addition to other items, must identify the inspection program used; identify the portion or segment of the inspection program accomplished; and contain a statement that the inspection was performed in accordance with the instructions and procedures for that program.

  d.	Questions continue regarding multiple entries for 100-hour/annual inspections. As discussed in paragraph 5c, neither part 43 nor part 91 requires separate records to be kept. Section 43.11, however, requires persons approving or disapproving equipment for return to service, after any required inspection, to make an entry in the record of that equipment. Therefore, when an owner maintains a single record, the entry of the 100-hour or annual inspection is made in that record. If the owner maintains separate records for the airframe, powerplants, and propellers, the entry for the 100-hour inspection is entered in each, while the annual inspection is only required to be entered into the airframe record.

11. DISCREPANCY LISTS.

  a.	Before to October 15, 1982, issuance of discrepancy lists (or lists of defects) to owners or operators was appropriate only in connection with annual inspections under part 91; inspections under section 135.41 l(a)(1); inspection programs under part 125; and inspections under section 91.217. Now, section 43.11 requires that a discrepancy list be prepared by a person performing any inspection required by parts 91,125, or section 135.41 l(a)(1).

  b.	When a discrepancy list is provided to an owner or operator, it says in effect, except for these discrepancies, the item inspected is airworthy. It is imperative, therefore, that inspections be complete and that all discrepancies appear in the list. When circumstances dictate that an inspection be terminated before it is completed, the maintenance record should clearly indicate that the inspection was discontinued. The entry should meet all the other requirements of section 43.11.

  c.	It is no longer a requirement that copies of discrepancy lists be forwarded to the local Flight Standards District Office (FSDO).

  d.	Discrepancy lists (or lists of defects) are part of the maintenance record and the owner/operator is responsible to maintain that record in accordance with section 91.417(b)(3). The entry made by maintenance personnel in the maintenance record should reference the discrepancy list when a list is issued.

12. LOST OR DESTROYED RECORDS. Occasionally, the records for an aircraft are lost or destroyed. In order to re-construct them, it is necessary to establish the total time-in-service of the airframe. This can be done by reference to other records that reflect the time-in-service; research of records maintained by repair facilities; and reference to records maintained by individual mechanics, etc. When these things have been done and the record is still incomplete, the owner/operator may make a notarized statement in the new record describing the loss and establishing the time-in-service based on the research and the best estimate of time-in-service.

  a.	The current status of applicable AD's may present a more formidable problem. This may require a detailed inspection by maintenance personnel to establish that the applicable AD's have been complied with. It can readily be seen that this could entail considerable time, expense, and in some instances, might require recompliance with the AD.

  b.	Other items required by section 91.417(a)(2), such as the current status of life-limited parts, time since last overhaul, current inspection status, and current list of major alterations, may present difficult problems. Some items may be easier to reestablish than others, but all are problems. Losing maintenance records can be troublesome, costly, and time consuming. Safekeeping of the records is an integral part of a good record keeping system.

13. COMPUTERIZED RECORDS. There is a growing trend toward computerized maintenance records. Many of these systems are offered to owners/operators on a commercial basis. While these are excellent scheduling systems, alone they normally do not meet the requirements of sections 43.9 or 91.417. The owner/operator who uses such a system is required to ensure that it provides the information required by section 91.417, including signatures. If not, modification to make them complete is the owner' s/operator's responsibility and that responsibility may not be delegated.

14. PUBLIC AIRCRAFT. Prospective purchasers of aircraft that have been used as public aircraft, should be aware that public aircraft may not be subject to the certification and maintenance requirements in Title 14 of the Code of Federal Regulations and may not have records that meet the requirements of section 91.417. Considerable research may be involved in establishing the required records when these aircraft are purchased and brought into civil aviation. The aircraft may not be certificated or used without such records.

15.	LIFE-LIMITED PARTS.

  a.	Present day aircraft and powerplants commonly have life-limited parts installed. These life limits may be referred to as retirement times, service life limitations, parts retirement limitations, retirement life limits, life limitations, or other such terminology and may be expressed in hours, cycles of operation, or calendar time. They are set forth in type certificate data sheets (TCDS), AD's, or the limitations section of FAA-approved airplane or rotorcraft flight manuals. Additionally, instructions for continued airworthiness, which require life-limits be specified, may apply (See CFR 23 Appendix G and CFR 27 Appendix A).

  b.	Section 91.417(a)(2)(ii) requires the owner or operator of an aircraft with such parts installed to have records containing the current status of these parts. Many owners/operators have found it advantageous to have a separate record for such parts showing the name of the part, part number, serial number, date of installation, total time-in-service, date removed, and signature and certificate number of the person installing or removing the part. A separate record, as described, facilitates transferring the record with the part in the event the part is removed and later reinstailed or installed on another aircraft or engine. If a separate record is not kept, the aircraft record must contain sufficient information to clearly establish the status of the life-limited parts installed.

16.	MAINTENANCE RELEASE.

  a.	In addition to those requirements discussed previously, section 43.9 requires that major repairs and alterations be recorded as indicated in appendix B of part 43, (i.e., on FAA Form 337). An exception is provided in paragraph (b) of that appendix, which allows repair stations certificated under part 145 to use a maintenance release in lieu of the form for major repairs (and only major repairs).

  b.	The maintenance release must contain the information specified in paragraph (b)(1), (2) and (3), appendix B of part 43, be made a part of the aircraft maintenance record, and retained by the owner/operator as specified in section 91.417. The maintenance release is usually a special document (normally a tag) and is attached to the product when it is approved for return to service. The maintenance release may, however, be on a copy of the work order written for the product. When this is done (for major repairs only) the entry on the work order must meet paragraph (b)(1), (2), and (3) of the appendix. That is to say that the Repair Station is required to give the owner:
	(1)	the customers work order upon which the repair is recorded;
	(2)	a signed copy of the work order; and 
	(3)	a maintenance release which has been signed by an authorized representative of the company. In some cases, a work order and a maintenance release may be a different document. Both must be supplied to the customer.

  c.	Some repair stations use what they call a maintenance release for other than major repairs. This is sometimes a tag and sometimes information on a work order. When this is done, all of the requirements of section 43.9 must be met (paragraph (b)(3), appendix B, not applicable) and the document is to be made and retained as part of the maintenance records under section 91.417 per discussion in paragraph 5c.

17. FAA FORM 337, MAJOR REPAIR AND ALTERATION.

  a.	Major repairs and alterations are to be recorded on FAA Form 337, as stated in paragraph 16. This form is executed by the person making the repair or alteration. Provisions are made on the form for a person other than that person performing the work to approve the repair or alteration for return to service.

  b.	These forms are now required to be made part of the maintenance record of the product repaired or altered and retained in accordance with section 91.417.

  c.	Detailed instructions for use of this form are contained in AC 43.9-1, Instructions for Completion of FAA Form 337, current edition.

  d.	Some manufacturers have initiated a policy of indicating, on their service letters and bulletins, and other documents dealing with changes to their aircraft, whether or not the changes constitute major repairs or alterations. Some manufacturers also indicate that the responsibility for completing FAA Form 337 lies with the person accomplishing the repairs or alterations and cannot be delegated. When there is a question, it is advisable to contact the local FSDO for guidance.

18. TESTS AND INSPECTIONS FOR ALTIMETER SYSTEMS, ALTITUDE REPORTING EQUIPMENT, AND AIR TRAFFIC CONTROL (ATC) TRANSPONDERS. The recordation requirements for these tests and inspections are the same as for other maintenance. There are essentially three tests and inspections (the altimeter system, the transponder system, and the data correspondence test), each of which may be subdivided relative to who may perform specific portions of the test. The basic authorization for performing these tests and inspections, found in section 43.3, is supplemented by sections 91.411 and 91.413. When multiple persons are involved in the performance of tests and inspections, care must be exercised to insure proper authorization under these three sections and compliance with sections 43.9 and 43.9(a)(3) in particular.

19. BEFORE YOU BUY. This is the proper time to take a close look at the maintenance records of any used aircraft you expect to purchase. A well-kept set of maintenance records, which properly identifies all previously performed maintenance, alterations, and AD compliances, is generally a good indicator of the aircraft condition. This is not always the case, but in any event, before you buy, require the owner to produce the maintenance records for your examination, and require correction of any discrepancies found on the aircraft or in the records. Many prospective owners have found it advantageous to have a reliable unbiased maintenance person examine the maintenance records, as well as the aircraft, before negotiations have progressed too far. If the aircraft is purchased, take the time to review and learn the system of the previous owner to ensure compliance and continuity when you modify or continue that system.

Thomas E. Stuckey
Acting Director,
Flight Standards Service

APPENDIX 1. AIRWORTHINESS DIRECTIVE COMPLIANCE RECORD (SUGGESTED FORMAT)