SAIB ACE-97-03 —

No. ACE-97-03 May 15, 1997

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 Information Bulletin is to advise operators of Luscombe Model 8, 8A, 8B, 8C, 8D, 8E, 8F, and T-8F airplanes, that the Federal Aviation Administration (FAA) and the Type Certificate (TC) holder, The Don Luscombe Aviation History Foundation (DLAHF) strongly advises routine inspection and maintenance of the airframe for corrosion, with particular attention to the internal structure of the wings, in accordance with 14 CFR Part 43.

BACKGROUND:

The Luscombe Model 8 series airplanes were type certificated and produced from 1938 to 1948. Based on the age of the aircraft and the lack of manufacturer technical support of the type certificate for many years, adequate maintenance instructions (for certain aspects) of the Luscombe model aircraft have not been readily available. Luscombe aircraft with metal wings were manufactured with a limited number of removable access panels for routine maintenance.

The FAA recently issued an Airworthiness Directive (AD) which requires a one time inspection of the wing spars for intergranular corrosion. This AD was based on service difficulty reports of intergranular corrosion of the wing spars on the Luscombe Model 8 series. (Intergranular corrosion can occur in high-strength aluminum alloys if they have been improperly heat treated during the manufacturing process.) As a result of this recent AD action, as well as restorations and re-skinning of the wings on the Luscombe Model 8 series throughout the life of these aircraft, the TC holder, DLAHF, has received reports of various forms of corrosion and contamination within the structure of the wings.

Due to the age of the Luscombe aircraft fleet, and the limited access to the wing internal structure, corrosion due to environmental effects and/or corrosion from bird and rodent infestation should be addressed by annual maintenance inspections.

The TC holder, DLAHF, has developed a kit (DLAHF kit #8007) which installs 4 additional inspection holes and modifies the wing tip faring to permit permanent access to the internal structure of the wings. Additionally, there exists several Supplemental Type Certificates (STC) for the installation of inspection holes which are FAA approved. Advisory Circular (AC) No. 43-4A, Corrosion Control for Aircraft, dated 7/25/91, provides information on corrosion theory, effects of corrosion, corrosion prone areas, and preventative maintenance, inspection requirements, and corrosion removal techniques.

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RECOMMENDATION:

As soon as practical, for Luscombe Model 8, 8A, 8B, 8C, 8D, 8E, 8F, and T-8F airplanes, the FAA recommends installing the removable inspection access holes in accordance with the DLAHF Service Recommendation #2 dated December 15, 1993, REVISED November 21, 1995, or other FAA approved installation. Additionally, the FAA recommends conducting repetitive inspections of the wing spars, on an annual basis, for signs of corrosion which may be the result of environmental effects and/or corrosion from bird and rodent infestation and fecal contamination.

FOR FURTHER INFORMATION CONTACT:

Lirio Liu, Aerospace Engineer, Federal Aviation Administration, Los Angeles Aircraft Certification Office, 3960 Paramount Blvd., Lakewood, CA 90712-4137, (562) 627-5229.