2,200-Pound Block of Swiss Cheese


What started out as a normal workday for the powerplants work center, actually turned out to be a hectic night. Fortunately, the results were not near as dire as they could have been. Unfortunately, the event could have been com­pletely avoided had we just followed proper procedures. We did, however, answer a very important question.

What do you get when you combine a routine maintenance action with miscommunication and maintenance not done by the book? A 2,200-pound block of Swiss cheese crashing to the deck!

In preparation for a functional check flight (FCF) for the following morning, the night check desk chief tasked our work center with dropping the inboard wing drop tank from aircraft 401 at the evening maintenance meeting.

Our work center was sidetracked with a higher priority job and after four hours, we were asked by the desk if we had completed the drop tank removal. Just to be sure about the maintenance evolution the shift supervisor and I, the leading petty officer (both collateral duty inspectors [CDIs]), went to maintenance control to confirm which aircraft needed its station seven-drop tank removed. After asking the maintenance control­ler to confirm the aircraft and station to be dropped, we found him working another jet issue and responded, “Yeah, 402, since it needs an FCF tomorrow.” There were many missed opportuni­ties that should have been avoided.

Missed opportunity No. 1: Wrong aircraft— 401 or 402.

We immediately headed back to the work center and told the shop to start checking out the appropriate tools for a drop tank removal and meet us on the flight line.

Missed opportunity No. 2: Neither the LPO, nor the other CDI qualified mechanic, checked the in-work status of the main­tenance action in NALCOMIS.

Missed opportunity No. 3: Neither of us brought a checklist for drop tank removal to the flight line.

Missed opportunity No. 4: We never established who would lead the evolution and who would inspect as CDI.

By the time we made it to the jet, our young Sailors had completely prepared the job site. The aft mount and I-cable were already removed and wooden pallets were placed under the tank (we did not have a drop tank cart available at the time). With a jet turning both engines directly adjacent to aircraft 402, the noise level was pretty high.

When the shift supervisor went up to the tank, he incorrectly verified the fuel quantity by knocking on the outside to see if it sounded empty. The supervisor was unable to hear any sound coming from the tank since the adjacent aircraft was turning, but deemed it empty and carried on. I asked him if the tank was empty and the shift supervisor confirmed that it was in fact empty. That was missed opportunity No. 5.

With a mistakenly empty fuel tank ready to be dropped, the supervisor positioned himself at the front of the drop tank and locked arms with his partner on the other side, and the other two personnel positioned themselves in the back and locked arms. Due to a previous hand injury, I took my spot at the weapons rack to unlock the release mechanism. I yelled the requisite, “Ready front? Ready back?” My crew replied accordingly, signi­fying they heard me and were ready to receive the weight. At this point, I unlocked the suspension rack and the external tank fell through their arms and landed squarely on the pallets positioned underneath.

As soon as the tank fell, I immediately checked to ensure no one was injured. After determining that no one had been hurt, I opened the fuel tank lid and discovered the tank was completely full of jet fuel.

We learned many extremely important lessons from this unfortunate event that we should have never had to learn. First and foremost, work center leadership failed from the beginning by not putting the maintenance action into an in-work status. If the proper time had been spent ensuring proper documentation, maintenance would not have been performed on the wrong air­craft (401 vs. 402) and the miscommunication between the work center and maintenance control desk would have been easily identified.

Second, the publications checklist (LWS-460) was not with us at the time of the evolution. Had it been, maintenance would have been done by the book. The fuel level would have been correctly checked by removing the fuel cap and visually verifying that the tank was empty instead of simply slapping it on the side to hear if it was empty.

Third, even with these multiple mistakes made, we com­pletely circumnavigated the quality assurance process of prevent­ing maintenance mistakes by not establishing the leader of the evolution and CDI to verify proper maintenance was achieved.

Since the incident, intensive training was conducted about the mishap and steps to be taken to prevent a reoccurrence. Work center leadership created a maintenance evolution brief, highlighting assignment of team lead, team members, and CDI for each event. The most crucial aspect of the brief is that it translates to all maintenance actions. This ensures clear commu­nication between personnel and promotes safety by eliminating and mitigating risks. Overall, the squadron is lucky this had not happened before and steps have been put in place to ensure it does not happen again.


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