B737-900
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 160; Flight Crew Total 18000; Flight Crew Type 10000
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Human Factors; Incorrect / Not Installed / Unavailable Part
Thought the loud squeal during flight was a bad window seal. Upon Maintenance Inspection; they found a total of 17 bolts missing between the four inspection panels in nose gear compartment. The remainder of the bolts you could loosen with your fingers. The differential pressure with the loose plates was making the noise. Safety concern.
Reporter stated he was flying a B737-900 aircraft. The loud squeal sounded like it was coming from the Number 3 cockpit side window. The aircraft maintained cabin pressure without any issues indicated. He could not find any previous discrepancies involving a pressure leak or loud squeals and was unable to determine if the aircraft had been in a Maintenance Check recently.Reporter stated Contract Maintenance was called to the aircraft; but these Aircraft Maintenance Technicians (AMTs) were very well trained employees of an International Flag Carrier that operated the same type of aircraft in the area. They performed a Cabin Pressurization Check and isolated the squeal sound to the nose landing gear compartment pressure access panels. The AMTs noted that the hex bolts used to attach the four pressure panels appeared to be too long; had been loosening up from vibration and backing out of the attach holes. Correct length of bolts were installed; another Cabin Pressurization Check and the aircraft released for service.
B737-900 pilot reports a loud squeal inflight; no pressurization problems noted. Contract Aircraft Maintenance Technicians (AMTs); found four pressurized access panels in the nose landing gear compartment with 17 bolts missing and others working loose.