My last mission while assigned to A Company, 7th Battalion, 101st Aviation was a recovery mission of a UH-60 Blackhawk Medevac helicopter that had struck power transmission lines at the north edge of the Fort Knox military reservation along the Salt River. The UH-60 had been flying a Night Vision Goggle (NVG) training mission with they struck 2 power lines. One was cut by the wire strike protection device above the windscreen and a second wire was cut by one of the main rotor blades. After the wire contact, the pilot on the controls successfully landed the aircraft under a second set of power lines in a field just off the Ft. Knox reservation.
The landing site was on the north side of the Salt river at the end of Katherine Station Road. I believe the pilot of the UH-60 received a broken wing award for safely landing that aircraft when I’m sure just about every warning light in the cockpit was illuminated. Even with filters, that many warning lights illuminating in the cockpit had to affect his goggle performance. Our job on the mission was to recover the aircraft back to Godman Army Airfield on Fort Knox.
The incident had occurred more than 24 hours prior to our mission assignment as the Army Safety Center accident investigation team had cleared the site before we arrived, this allowed us to remove the aircraft from the crash site. Our aviation support maintenance unit 8th Battalion 101 Aviation, had personnel on site to rig the UH-60 for recovery with a sling. All I had to do was fly to the site and coordinate with them to recover the aircraft.
It was August 1993, (I left the unit shortly afterward to my next assignment as a student at Austin Peay State University) and I was pretty sure that this would be my last mission as Predator 20 (Our commander had changed our call-sign to this aggressive name because he felt the old one was Wimpy, go figure). This mission was both exciting for me and also a bit sad.
We arrived and landed at the site without incident. It was a clear and calm day, with temperatures in the 70’s and almost no wind. Just about as good as you could hope for on this kind of mission. After we shutdown I located the maintenance team leader and we discussed how I wanted to execute the recovery. The big question was: "Leave the main rotor blades on the Blackhawk or take them off?" If we moved the aircraft with blades on we were limited to 40 knots airspeed. Blades off we could fly 90 knots. Since Godman Army Airfield on Ft, Knox was only 10 miles or so away, I opted for blades on to save time.
Then came the silly question: “Do you want to pick it up where it is at?” Since it was resting underneath a set of high voltage transmission power lines, I said: "No". I suggested they move it about 100 yards away from the power lines where I could safely hook up to it. They dutifully hooked up a tow bar and towed it to the spot I wanted to use as a pickup zone (PZ).
While waiting for the UH-60 to be moved, they used a Heavy Expanded Mobility Tactical Truck (HEMTT) tanker to refuel my Chinook (It was on site to defuel the Blackhawk anyway) and my crew and I ate our lunch while the Blackhawk was prepared as an external load. The Blackhawk was rigged with a recovery sling. The sling looped around the 4 main rotor blade roots and a fifth leg looped around the tail section forward of the tail rotor. The main section of the sling was roughly 100 foot and all together the rigging was about 130 feet long.
Once rigged and inspected by my Flight Engineer, the sling was laid out ninety degrees from the Blackhawk to the south of the aircraft and we approached for pickup from the east. The sling was long enough that we could land over the clevis and the Flight Engineer then merely reached down through the hook access in the floor, grabbed the clevis and put it on the center hook. No external hookup man at a hover was required.
We completed the before takeoff checks and slowly brought the Chinook to a hover, then continued up to about 100 feet. I was explaining to my co-pilot that with a heavy load and a long sling, you really didn’t have to worry much about being perfectly centered over the load. As tension was applied to the sling, the aircraft was automatically centered over the load. We chose the westward facing approach for all the correct reasons; the wind was from the west (Less than 5 mph) there was a nice tree line that would give us a nice hover reference for an out of ground effect hover and we wanted to go that way anyway, so less turns were involved.
Picking up a heavy load with a long sling had other considerations that you normally do not deal with, the main one was that you were already in an out of ground effect (OOGE) hover. An out of ground effect hover was when you were at a hover that was higher than half the diameter of your rotor system, (30 feet in a Chinook). When you hovered in ground effect, you had the benefit of the ground giving you extra lift by additional resistance to the downward air flow.
You had to be especially careful when hovering OOGE because you could get in a situation called “Settling with Power” or more correctly called a “Vortex Ring State”. When you hovered OOGE, your rotor down flow could re-circulate causing a down draft and if the downward air speed exceeds 300 feet per minute. You could quickly get into a situation where this downdraft could exceed your power available to counteract it and cause a crash. Because of this, you didn’t loiter in an OOGE hover.
We quickly did a before takeoff check and slowly I nosed the helicopter over and we accelerated to about 40 knots. We climbed to where the load was about 500 feet above the nearest obstacle (The forest) and turned south just before West Point, KY. We flew parallel but not over Highway 31W southward toward Fort Knox and I radioed the tower at Godman Army Airfield (GAAF) that we were on final visual approach with an external load and wanted to go to the maintenance ramp to set down the load.
We were cleared for landing runway 180 and then cleared to the maintenance ramp adjacent to the hangar to set down the crippled Blackhawk. We spent about a minute hovering over the pad while the Blackhawk slowly spun in a circle, my Flight Engineer wanted to set it down properly oriented on the pad facing south and I indulged him. Once down, we hovered to the right and released the clevis over the grass and we were cleared for immediate takeoff to the southeast. There was a no-fly area around the gold vault south of the airfield that we avoided then we made our return flight to Fort Campbell, mission complete.
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