"Dec 1970, Inflight Blade(s) Mesh Incident"
by Larry Fann
The photos are from very old Super 8 movie film of a "Dec 1970 incident"; (probably Dec 8th). Until VHPA at Ft. Worth in 2004 I'd never met anyone who could verify my telling of this incident. At the new museum dedication near Mineral Wells, I ran into Tom Leverenz, who remembered the event. I had not seen Tom since early 1971 at Can Tho.
Copilot was Joe Holley and I'm ashamed to say I don't remember the crew or the aircraft tail number.
AS BEST I REMEMBER, HERE IS WHAT HAPPENED
My call sign was Hillclimber 20 (second platoon IP). I was giving Joe Holley a one-day checkout in the Super C with L-7C engines. (You may recall that in late 1970 the L-11 engines were blowing up so we put the L-7C engines back on and made them "Super C minus" aircraft.) We had flown flame munitions drops for 4 or 5 hours in the morning with no evidence of anything wrong in the rigging of the main rotor system. We were on our first afternoon mission. Clouds had built around the mountains and there was occasional light to moderate turbulence. On final to a ridgetop near the top of one of the 7-sister Mountains with a sling load of lumber for bunkers, it sounded like we took machine gun hits. I remember scanning the gages and asking the crew if anyone was hit. Nothing seemed wrong system wise and the crew responded that they were all ok so we continued the approach. When I pulled power to arrest the descent ALL HELL broke loose. The vibration was so bad we could not see the instruments and the cockpit filled with dust. I punched off the lumber and entered auto-rotation to the side of the mountain. I don't remember the touchdown but with brakes applied we were sliding backwards on the steep terrain and it looked like the front blades would strike the slope in front of us. I remember changing hands on the cyclic and turning off "SAS" (I remember thinking we had "SAS chatter"). I also remember thinking we would turn sideways in our backwards slide and roll over if I didn't do something. I pulled power, lifted off (no SAS but I don't remember much about this short, change of location flight) and climbed the 1-2 hundred feet necessary to see the original landing zone. I nosed over to get there. As the rear wheels touched down (hit the ground) in the flare I changed hands on the cyclic again, pulled both engine condition levers to "off", put my transmitter on guard and made a mayday call. I don't remember Joe doing anything but then I did not communicate with him or the crew during this time (Joe I apologize for that poor crew coordination example). As the front wheels settled to the ground and the main rotor RPM began to decay, the vibration was immediately reduced. As I recall, the FE exited the ramp area at our first point of landing and had to climb the slope to reach us (My memory is hazy on this point???) I specifically remember seeing the right forward door gunner trying to run away from the aircraft after we landed the 2nd time. He had so much adrenalin pumping he kept falling down and getting up; he did not have control of his legs. I remember thinking about jettisoning my door but deciding against it (it’s a long drop). We all exited and met near some very tall rocks a short distance away. Almost immediately the 235th Cobras we had worked with during flame munitions drops that morning arrived in response to our May Day call and began circling at very low altitude. I've always believed they were daring "Charlie" to show himself or even to think about getting to us in the rocks. I have a special place in my heart for Cobra pilots even today!
The cause of this event turned out to be a Main Rotor drive train that and not been properly synced when put back together following work on a transmission seal. The rivets on the rain shield were 6 inches out of sync (the tolerance is + or - 1/8th inch). In the turbulence the front blades had led and the aft blades had lagged just enough for the leading edge of the front blades to contact the trailing edge of the aft blades. The stress on the blades when I added power did the rest. I thank God for Boeing's strong M/R spar.