Every week or so, a Dash 8 would arrive at the airport about 50 miles from camp to re-provision the camp and change out some crews. All four machines in the camp (Two AStars and two Long Rangers) would meet the Dash 8 at the airport and long-line the groceries, supplies and equipment back to camp. On this day, the two AStar pilots were headed home and two fresh pilots were shipping in.
It was a beautiful summer day in July, and three of us had landed at the airport in advance of the Dash’s arrival. I had shut down the Long Ranger that I was operating, and one of the AStars landed about 60 feet away, and had started his short cool-down. The pilot had closed the throttle and was about 30 seconds into his spin-down when the second AStar announced its arrival and quickly did a no-hover landing from behind the first AStar – close beside him. When the dust cleared, both machines were tied-down and we waited for the arrival of the Dash-8 and the new AStar drivers.
When the airplane arrived, we spent about an hour helping to build the loads for the trips back to camp, and two of the AStar pilots prepared to board the aircraft home. One of the arriving AStar pilots started his pre-flight, and he identified a flat spot on the top aft section of the tail rotor drive shaft cover.
As it turns out, we finally concluded that the downwash from the arriving second AStar had caused one of the slow moving main rotor blades of the first AStar to flap down and strike the tail rotor drive shaft cover. In all of the dust and noise of the arrival, the blade-strike had gone undetected. An engineer was immediately called to inspect the blades, the drive shaft cover, and the drive shaft for damage – fortunately there was none however, the potential for disaster was significant. The incident was sobering, particularly in the context of an otherwise perfectly pleasant last-day-of-the-tour for two of our pilots.
I must confess that I have a habit of asking myself repeatedly what could have been done to prevent this event from occurring:
- Could I have waved-off the second AStar as it was on the approach to land?
- What prompted the arriving AStar pilot to land so close to the first aircraft while its blades were still turning?
- What prompted the arriving pilot to land so close when the entire ramp was otherwise empty?
- What prompted the arriving AStar pilot to land so close without knowing if the throttle had been closed or if the pilot of the aircraft on the ground was ready for another arrival in close proximity?
- Why didn’t the out-going pilot identify the deficiency in his post-flight turnaround inspection of the aircraft?
- Should the company have had a policy on the landing of aircraft in close proximity to one another if there are better less-proximate alternatives?
- Finally, the most chilling question is, what could have happened if damage to the tail rotor drive shaft had gone undetected?
Fred Jones is the president/CEO of the Helicopter Association of Canada and a regular contributor to Helicopters magazine.