Main Rotor Blade Defect
.....................................................................................................................................................................................
Mid 1971 we were called as a Troop (F Troop) to search for part of a Navy Main Rotor Blade. A navy helicopter had come apart in flight near their river base. They had recovered one end of a Main Rotor Blade that looked like it had been cut. The second piece was needed to help determine if the blade had been cut as sabotage or was it a manufacturing defect.
The swampy area had tree/brush stumps that made the search difficult. We were unable to find the second end of the Main Rotor Blade. At lunch in the Navy mess hall, we had discussed how we were flying our Cobras on the same Main Rotor Blades. Didn’t seem to bother anyone as we discussed this or during the remainder of our tours.
A couple of years later I was flying Cobras at Fort Stewart, Georgia. Based on a maintenance bulletin our maintenance inspected our Cobra Main Rotor Blades. Turned out that about half of our 21 Cobras had at least one blade with a defect similar to the defect that brought the Navy helicopter down.
A Google search reference to this Maintenance Bulletin is:
TB 55-1520-243-50-1 ULTRASONIC INSPECTION OF 540-011 SERIES MAIN ROTOR BLADES, UH-1 UH-1M, AH-1G, TH-1G AND AH-1S HELICOPTERS