NADEP Safety Officer Corrects Incorrect Fix

What do you do when you discover that the approved fix for a dangerous airframe problem will actually cause more damage than good? Well, if you are Cris Sonnichsen, a sheet metal mechanic at Naval Air Depot (NADEP) Cherry Point, North Carolina, you fix the fix. Sonnichsen was performing maintenance on a Sikorsky MH-53E Sea Dragon helicopter, including installing the AYC 1306 modification.

The AYC 1306 modification, developed by Sikorsky Aircraft and the Japanese military, is the standard fix on the MH-53E to eliminate a bulkhead-cracking problem caused by preloaded stress. The fix included installing a strengthened support bracket to remove the preloaded condition and extend the life of the bulkhead.

While installing the AYC 1306 modification, Sonnichsen realized that the angle of the support bracket would create a new preloaded stress condition, one that would cause cracks to develop sooner. After Sonnichsen's discovery, engineering analysis found that the AYC 1306 bracket had been improperly formed, resulting in the new preloading condition.

An inspection of a second MH-53E helicopter found that its AYC 1306 bracket was also improperly formed. This led not only to the removal of the modification, but the subsequent inspection of every aircraft that had the bracket installed and a correction to all the other AYC 1306 modifications in the Navy's fleet.

During a ceremony to name Sonnichsen NADEP Cherry Point's Safety Officer of the Month, commanding officer colonel John Gumbel said, "Mr. Sonnichsen's attention to detail is just one example of the level of professionalism that is common throughout the depot workforce. The artisans on the floor are the last line of defense against a defective product from a supplier, engineering error, or wear on a critical component that is not called out for inspection."

Sonnichsen's attention to detail saved the U.S. Navy countless hours of maintenance and hundreds of thousands of dollars in replacement material and labor costs, not to mention the lives that could have been lost had the incorrect modification failed during a mission. -- By Dale Smith