Burned And Separated

The nose landing gear failed to extend when the gear was lowered for landing-a nose-gear "up" landing followed. Examination revealed the uplock bellcrank forward arm (p/n: 204303112) was bent and cracked through 90 percent of its material. It would not allow the uplock to disengage. The probable cause: severe side loading during landing at an unknown time. A new part was installed and a gear-rigging check made. No other problems were noted.

Key Takeaways:

• Multiple aircraft experienced diverse component failures, including a Cessna 177RG's nose landing gear, a Diamond DA40's exhaust heat exchanger and propeller mount nuts, a Slick magneto, and newly installed cylinders in a Teledyne Continental engine.
• The root causes of these failures varied, ranging from structural fatigue due to severe side loading and weld cracks, to internal component overheating and suspected manufacturing or installation defects leading to galled engine valves.
• Many problems were identified during routine inspections (e.g., 100-hour, 500-hour) or immediately after maintenance events (e.g., engine overhaul, propeller reseal), underscoring the importance of thorough checks.

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