AC 121-16

Historical

Advisory circular · Maintenance Certification Procedures

Approved
November 9, 1970
Last reviewed
October 25, 2024
This change
Canceled by Memo signed by John S. Duncan (AFS-1) and Richard Mathews (AFS-140); dated 12/04/2015.
Family
AC 121-16 · 1 version
14 CFR parts
121, 127

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed November 22, 2025.

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AC NO: AC lzl- 16 DA T E : 11/9m

ADVISORY

CIRCULAR DEPARTMENT OF TRANSPORTATION FEDERAL AVlAl’lON ADMINISTRATION 4 SUBJECT: MAINTENANCE CERTIFICATION PROCEDURES

1. PURPOSE. This advisory circular provides guidance for the preparation of an Operations Specifications - Preface Page which will afford nominal and reasonable relief from approved service and overhaul time limits when a part is borrowed from another operator.

2. APPLICABILITY. The type of Operations Specifications i, PrefaFe P-age .

illustrated in Appendix 1, Figure 1, and described in this advisory circular may be approved for use by Federal Aviation Regulations 121 and 127 operators.

3 . BACKGROUND. Instances have occurred where an operator in need of a part, which was not available from his own stock, was unable to borrow one because the time in service of the available unit exceeded his (the borrower's) approved service and overhaul time limit yet did not exceed that approved for the lender.

4 0 SCOPE AND LIMITATIONS. An operator may borrow and use a part provided by another operator for a maximum of 100 hours (or 50 landings if the service or overhaul time limit is controlled by the number of landings) even though the time in service of said unit exceeds his (the borrower's) approved service and overhaul time limit provided:

a. The part in question has a minimum time of 200 hours (or 100 landings if the service or overhaul time limit is controlled by the number of landings) remaining to service or overhaul in relation to the lender% approved service and overhaul time limit.

b. The part is not specifically life limited. In such a case, the part may not be operated beyond its approved life limit.

Initiated by: AFS-230

Page 2 AC 12146 l3/9p ' 5 . GENERAL, The provisions of this particular preface page, when authorized, apply equally to units borrowed from parts pool by parts pool participants.

L<iting Director , Flight Standards Service Flight Standards Service b , . .b

AC 121-16 Appendix 1 . w9 no Page 1 FIGURE 1. OPERATIONS SPECIFICATIONS - AIRCRAFT MAINTENANCE - PREFACE PAGE -

BORROWING PARTS

EXAMPLE

UNITED STATES OF AMERICA

FEDERAL AVIATION AGENCY

WASHINGTON

OPERATIONS SPECIFICATIONS

XYZ AIRLINES Form Approvcii.

Budgcl Rurvau No. O&ROTS.

AIRCRAFT MAINTENANCE - PREFACE PAGE

BORROWING PARTS XYZ Airlines, when in need, may borrow a part from another FAR 121 or 127 operator (or from a parts pool if the operator is a participant of a parts pool agreement) and may use such part for a maximum of 100 hours (or 50 landings if the service or overhaul time limit is controlled by the number of landings) even though the time in service of such part exceeds XYZ Airlines' apptoved service and overhaul time limit providing:

a. The part in question has a minimum time of 200 hours (or 100 landings if the service or overhaul time limit is controlled by the number of landings) remaining to service or overhaul in relation to the lender's approved service and overhaul time limit.

b. The part is not specifically life limited. In such a case, the park qy nbt be operated beyond its approved service life.

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Effective date Form FAA-1014 (5-47, 35285