Narrative:

During an annual inspection on a cessna 150B aircraft I discovered what appeared to be delamination on the landing gear bulkhead stiffener assembly. The landing gear bulkhead assembly is made of solid aluminum so I know it could not be delamination; but a result of corrosion. On initial inspection I could see that the lower row of rivets on the outboard side (the bucktails) were completely eroded away from the corrosion that had caused the aluminum to separate. Upon removal of the landing gear I could see much more damage that was present. On the lower portion of the component; the aluminum bar that supported the weight of the landing gear while the aircraft is airborne (the aluminum) had swelled up and separated from deep corrosion that had the appearance of delamination of a composite structure. Large pieces of aluminum had been flaking off for some time and had eroded between 1/16 to 1/8 of an inch in depth. With further inspection of the component; it was found that corrosion was present in the upper portion of the aluminum and had also began to swell; which in turn caused one rivet head to be sheared off from the tension that was put on the rivet. Parts of the upper portion of the [stiffener] component that was beginning to swell had also developed cracks from the expansion of the aluminum.

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Original NASA ASRS Text

Title: During an Annual Inspection a Mechanic with an IA (Inspection Authority) rating reports discovering severe exfoliating corrosion on both sides of a left landing gear bulkhead stiffener forging on a Cessna 150B. A major repair was required involving removing the left landing gear and replacing the entire bulkhead stiffener forging. Allegedly; there was no evidence of moisture; fuel; oil or hydraulic fluid contamination.

Narrative: During an Annual Inspection on a Cessna 150B aircraft I discovered what appeared to be delamination on the landing gear bulkhead stiffener assembly. The landing gear bulkhead assembly is made of solid aluminum so I know it could not be delamination; but a result of corrosion. On initial inspection I could see that the lower row of rivets on the outboard side (the bucktails) were completely eroded away from the corrosion that had caused the aluminum to separate. Upon removal of the landing gear I could see much more damage that was present. On the lower portion of the component; the aluminum bar that supported the weight of the landing gear while the aircraft is airborne (the aluminum) had swelled up and separated from deep corrosion that had the appearance of delamination of a composite structure. Large pieces of aluminum had been flaking off for some time and had eroded between 1/16 to 1/8 of an inch in depth. With further inspection of the component; it was found that corrosion was present in the upper portion of the aluminum and had also began to swell; which in turn caused one rivet head to be sheared off from the tension that was put on the rivet. Parts of the upper portion of the [stiffener] component that was beginning to swell had also developed cracks from the expansion of the aluminum.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.