More O-2 Single Engine Performance

submitted by: Alva Leon Matheson


One afternoon while flying on an infrequent daylight mission, the airplane suddenly began to vibrate very badly. I could not read the instruments and did not know the cause of the vibration. By individually retarding the throttles I determined that the source of the vibration was the front engine. I shut it down and the vibration ceased. I had solved the problem, but was faced with the additional challenge of what to do at my current location of 110 miles west of DaNang. I considered bailing out, but decided that since the airplane was still flyable, I would try to make it back to DaNang. (Flying west to Ubon was not feasible due to weather.) I lifted the nose toward North Vietnam and fired off both pods of rockets, but kept the pods on board, as I did not want them to fall into enemy hands if at all possible.
As I turned to the east, I called Crown (the rescue C-130 on station in Thailand) and advised them of my predicament and intentions. The airplane would not climb, but it was flyable. After a few minutes, I heard the transmission of a Covey OV-10 that was scheduled to be my relief. I called him and explained what had happened and he indicated that he would intercept me and fly with me back to DaNang. Sometime later I called Crown again and they replied that they could see me! They had flown into Laos and were flying along several thousand feet above me. They escorted me until I reached the fence eastbound. The outbound OV-10 (name omitted to protect the guilty) never did find me.
I returned to DaNang and made a rather uneventful landing. I taxied clear of the active into the arming area and shutdown the rear engine. I opened the forward cowling and observed the carnage. The exhaust manifold had come loose, but most frightening was the fact that the engine mounts were just seconds from departing the firewall. I still had no idea what was wrong so I walked out in front of the airplane and looked back at it. It was then that I noticed that most of one side of the propeller was missing! Later analysis revealed that it had been hit by a ZPU round.
About this time a lieutenant colonel from maintenance came up to me and said, “Lieutenant, what did you do to my airplane?” I replied, “I brought it back, sir,” and walked off.
Just another day at the office.
I looked in my logbook to find that the date of the incident was 22 September 1970 and the aircraft tail number was 21414. The following is written in the remarks:
“Severe vibration due to loss of front prop over Sekong river. This caused the exhaust manifold to separate and engine mounts to loosen. RTB.” The spelling of Sekong is in error. It should be Xe Kong and can readily be found on a map.