Which maintenance record entry best describes the action taken for a .125 inch deep dent in a straight section of 1/2 inch aluminum alloy tubing?

Which maintenance record entry best describes the action taken for a .125 inch deep dent in a straight section of 1/2 inch aluminum alloy tubing?

• A. Dented section removed and replaced with identical new tubing flared to 45 degrees
• B. Dent within acceptable limits, repair not necessary
• C. Dented section removed and replaced with identical new tubing flared to 37 degrees
• D. Dent repaired by smoothing and re-pressing the tubing

Answer: (C)

When tubing carries pressure in aircraft systems, any dented straight section should be replaced rather than repaired. The wall could be weakened, and attempting to smooth or re-press the tube can hide cracks or reduce thickness, leading to a failure under pressure. The correct remedy is to cut out the dented portion and install new tubing that matches the original specifications, including the correct flare dimension for the fittings. For this system, the standard flare angle for the tubing fittings is 37 degrees, so the replacement tubing must be flared to 37 degrees to ensure a proper seal and fit. A 45-degree flare would not mate correctly with the aircraft’s AN-type fittings and could cause leakage or misalignment. Hence, replacing the dented section with identical new tubing flared to 37 degrees is the appropriate maintenance entry.

When tubing carries pressure in aircraft systems, any dented straight section should be replaced rather than repaired. The wall could be weakened, and attempting to smooth or re-press the tube can hide cracks or reduce thickness, leading to a failure under pressure. The correct remedy is to cut out the dented portion and install new tubing that matches the original specifications, including the correct flare dimension for the fittings.

For this system, the standard flare angle for the tubing fittings is 37 degrees, so the replacement tubing must be flared to 37 degrees to ensure a proper seal and fit. A 45-degree flare would not mate correctly with the aircraft’s AN-type fittings and could cause leakage or misalignment. Hence, replacing the dented section with identical new tubing flared to 37 degrees is the appropriate maintenance entry.