An early test flight on an HUP aircraft, or could have been an XHJP, since they were basically the same, an incident occurred that I still find hard to believe. The flight was from the Morton flight ramp in front of the Quonset hut, and utilized a trailing bomb.
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The flight crew was pilot Jim
Ryan and Test Engineer Christ Christadola.
Christ was a large Greek with
very large hands (this becomes important later in this story).
Every thing was normal up to
the point of lift off, when the helicopter started climbing vertically much
faster than normal and transitioned to forward flight before the trailing bomb
was clear of the ground. We had a mad scramble to get clear of the cable before
we got caught up in it. A leg tangled in the cable would be a wild ride.
The helicopter went into a
tight 360 degree right turn about the time the trailing bomb was clear of the
ground and was coming back over the ramp with the trailing bomb about three
feet off the ground. Jack and I went flat on the ground to get out of the way. The bomb was swinging
laterally and nearly went in the Quonset hut open door.
Our thoughts were that Jim
Ryan had forgotten about the trailing
bomb and was just having some fun with us. The right turns continued and the
helicopter climbed to higher altitude.
Suddenly the helicopter
leveled off, stopped climbing, and was returning in a normal manner to the
ramp. A normal high hover was established and we received the trailing bomb as
the helicopter descended.
What Happened and Why?
It’s normal procedure for a
mechanic or engineer to install a rig pin in the flight controls to lock the
controls in neutral during calibration of the instrumentation on board. The rig pins are about 3/8 inch in diameter
and about 5 inches long, they pass thru all the quadrants in the control
system. One is for lateral/directional control and the other for
longitudinal/collective control. They have a large ring attached to the top of
the pin so they would not be forgotten, and would be easy to remove. You
guessed it!!
This day the rig pin for the
lateral/directional control couldn’t be located so a 3/8 diameter bolt was
substituted. This left only a hex head to grip and remove the pin. These pins
cannot be removed unless the controls are in absolute neutral, no load, and
usually require a little wiggle of the controls to pull them out.
The lateral/directional pin/bolt was not removed prior
to take off. This left the pilot with no control in those axis.
The right turns were not of his doing and he was climbing trying to clear the
trailing bomb. It’s hard to imagine being airborne with the lateral control
stick and the rudder pedals locked, and a trailing bomb hanging 50 feet below.
The location of this rig
pin/bolt is between the pilot’s feet.
“Christ” who is seated in the co-pilots seat, on the other side of the
console, was able to reach over between the pilot’s feet and remove the bolt
pulling on the hex head. It would have been nearly impossible for Jim Ryan not
to have a load on the controls while the bolt was being removed.
Christ managed to remove the
bolt and prevented what could have been a very serious accident. It happened no one was hurt and no damage
done, but we had a very angry pilot.
Bolts were no longer
substituted for rig pins.
Charles Kessler is a retired flight test engineer for
Boeing’s Vertol helicopter division (formerly Piasecki Helicopter Co.). He
joined Piesecki in 1947, in the company’s fourth year, and retired from Boeing
in 1983. During his 37-year career he took part in the testing of prototypes
and alterations of such models as the CH-47 Chinook and Sea Knight, the H-16,
HRP-2, and the V-107. He taught the stability augmentation system to the German
Luftwaffe. He has written about his experience in a blog called “Early
Helicopter Years,” which can be found at http://helicopterstory.blogspot.com/.
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