Narrative:

We were closing up the aircraft after the environmental control unit (ecu) installation. We looked in all the compartments for tools or any other items left in the aircraft. We looked at bolts and cotter pins and aggressively moved the flight controls to make sure the ecu installation hadn't caused any binding on any of them. We closed all the panels. We pushed the aircraft out: a pilot and one of the mechanics took it out for a ground run and an operational check flight. They came back with no problems noted other than the noise of the ecu and the tail-low attitude of the aircraft. Another mechanic and I got into the aircraft with a different pilot. We took off; flew around and listened to the ecu. It was really loud. The pilot commented that the aircraft was holding a lot of pedal; more than he was used to. We were discussing whether this could be related to the aft center of gravity (C.G.). We were hovering at the end of the runway. The pilot applied more pedal. There was a 'pop' and the pedals froze. The pilot rolled off the throttle to arrest the spin. The aircraft came to rest at the end of the runway with no damage to the aircraft or the passengers. We towed the aircraft back to the hangar; opened up the panels and found that when the bolt was installed in the bellcrank it failed to capture the bearing of the push-pull tube end. At least three airframe/powerplant (a/P) mechanics had looked inside this panel for tools and clearances of the [push/pull] tubes after the ecu installation and we had aggressively moved the pedals prior to the test flight. None of these actions revealed any problem. Corrective action recommended: provide an easier way to connect push-pull tubes and to check the installation. The [access] hole is too small and can only be accessed from the side of the aircraft - the mechanic must fully extend his arm to reach it.

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Original NASA ASRS Text

Title: Four Maintenance Technicians; including an Inspector; reported difficulties installing an Environmental Control System (ECS) Unit into a Bell 206L helicopter that resulted in the tail rotor push-pull control rod not being attached to a bellcrank clevis. Rod had separated during Operational Checks causing the Pilot to do a hovering auto-rotation.

Narrative: We were closing up the aircraft after the Environmental Control Unit (ECU) installation. We looked in all the compartments for tools or any other items left in the aircraft. We looked at bolts and cotter pins and aggressively moved the flight controls to make sure the ECU installation hadn't caused any binding on any of them. We closed all the panels. We pushed the aircraft out: a pilot and one of the mechanics took it out for a ground run and an Operational Check flight. They came back with no problems noted other than the noise of the ECU and the tail-low attitude of the aircraft. Another Mechanic and I got into the aircraft with a different Pilot. We took off; flew around and listened to the ECU. It was really loud. The Pilot commented that the aircraft was holding a lot of pedal; more than he was used to. We were discussing whether this could be related to the aft Center of Gravity (C.G.). We were hovering at the end of the runway. The Pilot applied more pedal. There was a 'pop' and the pedals froze. The pilot rolled off the throttle to arrest the spin. The aircraft came to rest at the end of the runway with no damage to the aircraft or the passengers. We towed the aircraft back to the hangar; opened up the panels and found that when the bolt was installed in the bellcrank it failed to capture the bearing of the push-pull tube end. At least three Airframe/Powerplant (A/P) mechanics had looked inside this panel for tools and clearances of the [push/pull] tubes after the ECU installation and we had aggressively moved the pedals prior to the test flight. None of these actions revealed any problem. Corrective action recommended: Provide an easier way to connect push-pull tubes and to check the installation. The [access] hole is too small and can only be accessed from the side of the aircraft - the Mechanic must fully extend his arm to reach it.

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.