Nose Down Jumbo AMU Magazine 2011

Nose Down Jumbo

By Sam Longo AME A&P

 

Midnight shift in the Line Maintenance Hangar was always a flurry of intense activity culminating with each airworthy aircraft departing for their designated departure gates. On most nights everything ran according to plan, but on this particular night Murphy’s Law was working overtime.

 

Beginning in the early 1970’s the Boeing 747 “Jumbo Jet” was the queen of Air Canada’s fleet. It was a robust, reliable airliner but like any aircraft in the business of commercial travel it still required its fair share of routine maintenance. It was a large complex aircraft with thousands of components and systems. You could work on it for a lifetime and still leave much of its inner workings unexplored. It was part of what made working on it particularly challenging and sometimes perhaps just a little intimidating.

 

The chain of events that lead to the “Nose Down Jumbo” incident unfolded on a typical midnight shift. I was working dayshift so I arrived on scene only to witness the aftermath, but every maintenance employee soon knew all the intimate details of the whole unfortunate story.

 

Apparently there was a landing gear “indication light” snag that had been worked on over the course of the shift. As morning approached it was time to test the repair. The Certified Aircraft Technician that was in charge came down from the flight deck to verify that the four main gear, and one nose gear pin were installed as per the procedure manual and all was well. He then returned to the flight deck to select the landing gear lever to the “Up” position.

 

Meanwhile down on the hangar floor a maintenance tow-crew was preparing to pick up another Boeing 747 from the terminal and tow it back to the hangar. The equipment required to complete their task was a tow tractor, a 747 tow-bar, and a full set of landing gear pins. This is where the story takes its first turn for the worst. The tool crib attendant informed the lead tow mechanic that he had the four main gear pins but had NO nose gear pins left in stock. In an honest attempt to get his job done properly, knowing full well that it was unsafe to tow an aircraft without first installing the landing gear pins, the lead tow mechanic simply walked over to the nearest 747 in the hangar and robbed the nose gear pin that he required.

 

The stage was now set, as the tow crew climbed into their tractor to depart, they were oblivious to the carnage unfolding behind them. Seconds later as the Certified Aircraft Technician on the 747 Flight Deck selected the landing gear lever up he and his colleagues were treated to a horrible sinking sensation followed by the metallic crunch of the still open nose gear doors being crushed by the mammoth aircrafts considerable weight. The first miracle was that no one was injured, and the second was that as the tail shot up, it was perfectly spaced between two hangar support beams, so the aircraft was spared any additional empennage damage. Still fixing the aircraft was far from cheap. Rumor had it that Boeing had to pull out the jigs in Seattle to manufacture a new set of landing gear doors costing the airline over 100 thousand dollars. Add to this the lost revenue having the big bird grounded for repairs and ultimately it was a very high price to pay for the lack of a $35 nose gear pin.

 

If we call on our Human Factors Training, there is much to be learned from this incident. The chain of events leading up to this unfortunate situation can be identified and rectified for future reference. Communication- a simple headset with a maintenance person standing watch at the nose during the crucial stage of the procedure could have easily saved the day. Fatigue- perhaps the headset idea would have come up if the maintenance personnel weren’t tired and nearing the end of a busy midnight shift. Equipment- lack of sufficient numbers of nose gear pins could have been easily remedied providing an inexpensive safety net. Company Norms- it was a very common practice to “rob” landing gear pins from hangar aircraft for towing purposes knowing that they would be replaced before the robbed aircraft was towed again. Lack of Manpower/ Pressure- the aircraft could have been placed on jacks for the test procedure but this would have required considerably more personnel and additional time.

 

Of course it is easy now to look back in hindsight and see the seemingly simple errors of our ways. The value of Human Factors training is to do exactly that, increasing our awareness so that we might better recognize and prevent those situations from occurring in the future. I firmly believe that it is an endeavor worthy of our pursuit.

 

On a more personal note, I have always felt extreme empathy for the unfortunate mechanic that pulled the nose gear pin on that fateful night. It was such an innocent mistake, done in the honest interest of getting his assigned task completed. As mechanics we had all done the exact same thing on various occasions without incident. As we all know, Murphy’s Law forever remains a random phenomenon; “there but for the grace of God go I”. Stay safe my friends.  

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