Class C mishap summary

Mech, Summer, 2004 by Gary Dennis

From March 23, 2004 to June 1,2004, the Navy had 25 class C's that involved 29 aircraft. The damage total was $1,734,225. This loss is incredible when you look at this short period (nine weeks) and realize these "small mishaps" almost equal two Class A's! The dollar cost is just one part of the problem. While we're in a war footing, the loss of readiness, and the extra man-hours spent on repairs is unacceptable. We must do better and must realize Class C mishaps are important. We need leaders to step up efforts to reduce all classes of mishaps.

* While a mech was balancing the No. 1 propeller on a KC-130T, the prop spinner departed the aircraft. The squadron then did a conditional inspection on all its aircraft. Eighteen other props were damaged in and around the retaining-ring groove, which holds the spinner to the propeller. The one involved in the mishap had similar damage because the expansion-ring bolt had been overtorqued.

The MIMs include procedures on bow to inspect and install a propeller. They also govern the amount of torque to be applied. These torque limitations exist because of lessons learned from earlier mishaps. However, it's a common practice in some squadrons to omit the torque specification when installing a spinner. Maintainers simply tighten the expansion ring bolt, rather than use a torque wrench. This technique can cause an overtorque, which could crack the spinner's retaining-ring groove or allow it to delaminate enough for the expansion ring to separate. [This incident cost $143,563. This procedure was considered the norm for this squadron and its community. However, the norm often is not a "by the book" procedure, and reliance on it eventually will get you in trouble.--ADCS(AW) Gary Dennis, senior powerplants maintenance analyst, Naval Safety Center]

* Returning to base from a routine mission, the pilot of an FA-18C heard an audible warning about unsafe main landing gear. Shortly after lowering the gear handle, he heard another warning that the port main landing gear (PMLG) was not down and locked.

He called his wingman, who verified the PMLG was up and the gear doors were open partly. All efforts to lower the gear were unsuccessful. The pilot flew a full-flap, straight-in approach to an arrested landing on the runway. The aircraft landed, coming to rest just oft the left side of the runway at the end of the arresting-gear rollout. The damage cost $170,955.

An investigation found that a maintainer had failed to secure the rigid connecting link with an RCL bolt. He also didn't document the maintenance done and didn't give a passdown for the next shift. This incident begs for an answer to the question, "Where was the supervision?"

Human error was involved in eight other Class C mishaps this period. These incidents involved parking, towing and taxiing aircraft and cost $526,821.

If you want more information on groundcrew coordination or human factors, visit the web at www.safetycenter.navy.mil and do a search for "human factors" and "groundcrew coordination" or click on the aviation link. While you're there, click on media and read current or back issues of Mech, look for maintenance-related human-error photos, or check out our video section. Remember to work, play, and live ... safely.

Senior Chief Dennis is a maintenance analyst at the Naval Safety Center.