While this sounds like standard maintenance, SE79-49 is notable because it prompted a shift in how mechanics visually inspect these components. Before this letter, many mechanics relied on the "wiggle test"—physically shaking the control surface to feel for play. SE79-49 clarified that visual inspection and measurement of the bolt shank and the surrounding structure are necessary to catch wear before it becomes dangerous.
that corrected a latent failure mode in the propeller governor drive system of popular Cessna high-performance singles. While over 40 years old, compliance remains legally required via ADs. Any affected aircraft without documented proof of the SE79-49 modification (nut 61A20, 135 in-lb, safety wired) is not airworthy.
This document is intended for aircraft owners, maintenance technicians, and IA (Inspection Authorization) holders working with Cessna single-engine, high-performance aircraft (primarily the 200-series and 100-series models with constant speed propellers). Cessna Service Letter Se79 49
Cessna Service Letter SE79-49 (Revision 1, April 28, 1980) addresses the inspection and replacement of potentially cracked vertical fin aft attach bracket nutplates on Cessna 150/152 models. The service letter requires a one-time and recurring 100-hour inspection of the NAS1068A4 nutplates, which can be terminated by replacing them with authorized alternative hardware. The technical requirements of this letter are mandated by FAA AD 80-11-04. Read the full details on Scribd . Se 79-49 R1 | PDF - Scribd
~2–3 hours for skilled mechanic.
Under FAA regulations, all aircraft operated under Part 91 must undergo annual inspections per FAR 43, Appendix D. This appendix requires inspectors to examine “all hinges, fittings, and attachments for… corrosion.” SE79 49 provides the specific method for inspecting these fittings. Any competent IA (Inspection Authorization) performing an annual should follow the manufacturer’s recommended procedures, which include SE79 49.
Unlike surface corrosion, intergranular corrosion is . It can exist deep within the fitting without any visible pitting on the outside. By the time a mechanic sees a bulging or cracked fitting, the part may have lost over 50% of its load-bearing capacity. While this sounds like standard maintenance, SE79-49 is
If you are the owner of a vintage Cessna (models produced between the 1950s and 1980s), this Service Letter is likely referenced in your aircraft's maintenance history.
Later serial numbers incorporate the fix at the factory. that corrected a latent failure mode in the
Even without an AD, if a Part 91 aircraft crashes due to wing strut fitting corrosion that would have been found via SE79 49, the FAA can (and has) pursued certificate actions against owners and mechanics for failure to follow manufacturer maintenance instructions.
is a critical maintenance document that addresses the inspection and potential replacement of cracked nutplates in the vertical fin attachment area of various Cessna single-engine aircraft. Issued to ensure structural integrity, this letter is primarily associated with Airworthiness Directive (AD) 80-11-04 , which mandates recurring inspections to prevent catastrophic tail assembly separation. Purpose and Technical Scope
