Aircraft Have A History Of MLG Failure Due To Corrosion

The FAA has issued a Special Airworthiness Information Bulletin (SAIB) recommending strict adherence to recommended inspections of the main landing gear (MLG) on Luscombe Model 8 series airplanes.

According to the document, the Luscombe Model 8 series airplanes have a history of MLG failures due to internal corrosion of the MLG lower legs. The design of the lower leg allows for moisture to accumulate inside the leg above the axle, which makes it susceptible to corrosion. Internal surface treatment and regular inspection of the lower legs may help mitigate gear failures due to corrosion.

The FAA recommends that owners and operators of the affected airplanes follow the inspection procedures outlined in The Don Luscombe Aviation History Foundation (DLAHF) Service Recommendation (SR) #4, dated January 22, 1996. The DLAHF SR #4 provides instructions to install a drain hole in the lower portion of the leg, to perform repetitive inspections of the gear legs for corrosion, and to clean and seal the internal surfaces of the gear legs.

Steps 2 and 3 following the “Inspect” paragraph of DLAHF SR #4 provide instruction to tap the lower leg with a ball peen hammer to free rust flakes and to clean the legs internally with a wire brush before surface protection. In addition to these steps, we recommend the following actions be performed for rust removal:

• Clean legs internally with a cleansing muriatic acid wash
• Flush with water
• Allow legs to dry completely
• Treat with sealant epoxy paint as specified in Step 3 of DLAHF SR #4

The agency also recommends using x-ray or ultrasound inspection methods on the leg to axle joint as an effective way to detect internal rust during the initial or follow-on inspection of the gear leg.

These recommendations apply to both the conventional style and Silflex style MLG. The lower legs on the left and right side of the conventional MLG are identified with part number (P/N) 58383 and P/N 58383-1. The lower legs on the left and right side of the Silflex MLG are identified with P/N 2 083119-2. This recommendation also applies to parts manufacturer approval (PMA) landing gear leg parts produced by Univair Aircraft Corporation with P/N U58383 and P/N U58383-1.

(Source: FAA. Image from file)

FMI: SAIB