SAIB ACE-98-38

SPECIAL

AIRWORTHINESS

INFORMATION

BULLETIN

AIRCRAFT CERTIFICATION SERVICE 800 INDEPENDENCE AVENUE, S.W.

WASHINGTON, DC 20591

U.S. Department of Transportation Federal Aviation Administration

No. ACE-98-38 July 6, 1998

Published by: FAA, AFS-610, P.O. Box 26460, Oklahoma City, OK 73125 This is issued for informational purposes only and any recommendation for corrective action is not mandatory.

Introduction The purpose of this Special Airworthiness Info rmation Bulletin (SAIB) is to inform the owners/operators of Pilatus Britten-Norman BN2, BN2A, BN2B and BN2T Islanders and BN2A-MkIII Trislander aircraft of cracks that have been found in the wing sparcaps in the area of the top main landing gear thrust block.

Background Pilatus Britten-Norman reports that some owners/ operators have found cracks in the wing sparcaps in the region of the main landing gear upper thrust block. The cracks can extend horizontally and/or vertically from bolt or fastener holes. Consequently, Pilatus Britten-Norman has issued Service Bulletin BN2/SB.237 Issue 1, dated Octobe r 1, 1997, which details inspection procedures for the affected sparcap area.

Recommendation The FAA is recommending, but not requiring, that owners/operators of Pilatus Britten-Norman BN2, BN2A, BN2B and BN2T Islande rs and BN2A-MkIII Trislander aircraft pay special attention when inspecting the sparcap in the area of the ma in landing gear upper thrust blocks and follow the instructions presented in Service Bulletin BN2/SB.237. The FAA strongly recommends that in the event cracks are found, no further flight take place until the component(s) is replaced. A sparcap is considered primary structure and it may not be able to sustain design loads when degraded by cracks.

Copies of Pilatus Britten-Norman Service Bulletin BN2/SB.237 Issue 1, dated October 1, 1997, can be obtained from Pilatus Britten-Norman, Lt d., Bembridge, Isle of Wight, United Kingdom, PO35 5PR.

For Further Information Contact:

Mr. Roger P. Chudy, FAA, Small Airplane Directorate, ACE-112, 1201 Walnut, Suite 900, Kansas City, MO 64106, telephone: (816) 426-6934, fax: (816) 426-2169.