AD 89-12-01

89-12-01 LEARJET (Formerly GATES LEARJET): Amendment 39-6227.

Applicability: The following Learjet series airplanes and serial numbers, certificated in any category:

Model Number/Series Serial Number 24 24-100 through -357 25 25-003 through -373 28 28-001 through -005 29 29-001 through -004 35 35-001 through -646 36 36-001 through -058 55 55-001 through -134

Compliance: Required as indicated, unless previously accomplished.

To prevent failure of drag chute upon deployment, accomplish the following:

A. Within the next 10 hours time-in-service or 2 calendar weeks after the effective date of this AD, whichever occurs first, determine the manufacture date that is stamped on the drag chute riser, in accordance with the instructions provided in the following Learjet Service Bulletins:

Model/Series Service Bulletin 24 or 25 24/25-342A 28 or 29 28/29-25-3A 35 or 36 35/36-25-7A 55 55-25-4A

1. If the drag chute riser isdated prior to May 1987, reidentify the riser and reinstall the drag chute and canister, in accordance with the Accomplishment Instructions of the applicable service bulletin.

2. If the drag chute riser is dated May 1987 or later, accomplish either subparagraph a. or b., below:

a. Replace the suspect riser with a new riser, Learjet Part Number (P/N) 6600180- 16, or a riser dated prior to May 1987, in accordance with the applicable service bulletin; or

b. Remove the riser and install a placard stating "DRAG CHUTE INOPERATIVE" on the drag chute deploy handle and drag chute mechanism, in accordance with the Accomplishment Instructions of the applicable Learjet service bulletin listed above. This placard may be removed once the drag chute riser is replaced, in accordance with paragraph A.2.a., above.

B. Prior to return to service after reidentification or replacement of the drag chute riser, as required by paragraph A. of this AD, perform a drag chute control system adjustment and drag chute functional test, in accordance with paragraph 2.C.(2) (f) of the Accomplishment Instructions of the applicable Learjet Service Bulletin specified in paragraph A. of this AD (reference Learjet Maintenance Manual, Chapter 25-62-00).

C. An alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Wichita Aircraft Certification Office, FAA, Central Region.

D. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.

All persons affected by this directive who have not already received the appropriate service information from the manufacturer may obtain copies upon request to Learjet Corporation, P.O. Box 7707, Wichita, Kansas 67277. This information may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or at the FAA, Central Region, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas.

This amendment (39-6227, AD 89-12-01) becomes effective on July 3, 1989.