The Bugged equipment Caper 1955
By Russell E. Theisen
When I was in high school, I had joined the United States Marine Corps Reserve in 1953 and worked my way up to Sergeant. I worked in Avionics Shop for VMA-233. We flew the A4D Shy hawk Air craft.



I had taken several electronic training courses and was a Radio and Television Repair technician during the week days. We were having the (IG) Inspector General Inspection of the Air Wing one week end in November 1955. The IG Master Sergent Anderson senior (NCO) Non Commissioned Officer) of the IG team, stopped by my Avionics shop and said that he was having trouble with his ARN-21 TACAN (Tactical Air Communications and Navigation) system in the Generals Air Craft and he wanted to know if I could check it out and see what was wrong with it. He gave me a (TR) Trouble Report explaining that it just quit working.
I told him I would look at it. I said that I would make an attempt to fix it. He snickered and said “yea you do that”, and he left the avionics shop.
I sent some Marines out to the Generals Plane to remove it and bring it back to the shop for me to check it out.
They came back in about 3 minutes with the unit in hand.
I was suspicious since it took longer than that to remove the ARN-21 TACAN Transceiver from the Aircraft. I ask them “exactly where did you get the unit?”
They told me that it was not installed in the aircraft, but was in the stowage compartment. AH-AH, I smell a rat.
I thought that this is a bugged unit and they want me to try and fix it, as part if the Inspection of the Squadron.



I gave the unit a quick functional check and it was definitely a dead unit.
I went through a few preliminary checks and noticed the three tuned wave guide cavities were not tracking as they should. I started a log book of the problems found. It could not receive a signal nor transmit a signal. I told my Avionics group that this is definitely a bugged system, so we would trouble shoot it slightly differently than the TACAN Maintenance Manual proposed.
First I tuned the waveguide cavities completely out of the cavities. I noticed that they did not track and all four must track so I then disconnected the chain drive and reset them by hand. (This is something that the line Maintence procedures suggested that we never had to do, It was a Manufacturing Maintence procedure only). Next I checked all of the tubes and noticed that they all seemed to check OK. I next used a voltage test adapter on the tubes to check for the proper voltages on the tube elements. The voltages were much different than they should be.(This is a technique that I had used to repair Television Receivers, but it was not a line Maintenance procedure). After tracing the schematic signals we found several tubes had wrong signals.
I measured voltages and checked currents, resistors and capacitors, tube sockets, transformers etc. and I found about 12 problems that should never be found in an ARN-21 TACAN system.

I thought that I would just get it fixed just to see what the Inspector General would do.

I unsoldered several resistors that were marked correctly, but were not any where near the correct value.(In fact they were made of wood and just painted with the resistor markings)
I replaced several capacitors that were not correct. (They were just ceramic wafers marked as capacitors).
I replaced two pulse forming transformers that had open windings.
I drilled out and replaced two tube sockets that had broken pin feed-throughs to the sockets.

I then put all the bad parts in a shoe box. Tuned up the TACAN receiver, Got the Transponder to operate, tuned it to a local TV Channel 13 Transmitter that we had in the local neighborhood.(This was not the normal signal generator but it worked great as a quick check of the receiver sensitivity)

I worked through lunch when I was through, I had my line crew take it out to the IG Aircraft and Replace the one in the Air Craft. I took the Log and the Maintence paper work and all the repaired and replaced components and waited for the Master Sergent Anderson to stop by the shop to check on things.
He stopped by about 1500 (3:00 PM) to see how we were doing.
I said “Oh It is all fixed and we installed it back in the Generals Air Craft.” He shouted at me that “No you did not fix it, no body can”.
I told him that we found some strange things that should never be in a Manufactured ARN-21 TACAN. It would have never worked with all the problems that we had fixed”. The Master Sergent said “You did not fix that TACAN Unit, It could not be fixed” I said yes we did and we installed it in the Generals Aircraft. He went storming out of the shop to the Aircraft and verified the serial number of the unit in the Generals Aircraft,. Then the got a (UPS) Utility Power Supply, power and climbed in the make some electronic tests. After several minutes he climbed out of the A4D and went storming into the line shack. Here come a General, Lt Coronal, Major, a Captain, My Lt. Coronal Commanding Officer and the Master Sergeant. They wanted what the hell did you do to my TACAN ?
I said that I fixed it like you wanted me to according to the TR that you gave me. I have the bad parts in the shoe box and the Trouble Report Paper work documenting what I had to do to get it operational. It was in very bad condition before I worked on it, but it is working fine now. The General sent the Lt. Coronal out to check the serial number of the unit in the air craft.
While he was gone the General continued to tell me that I had not fixed that unit because it could not be fixed. It was designed not to work and it was a specially designed test unit that he had specially made to test avionics unit’s capabilities.
I said General if had knowned that you did not want it repaired, I would not have repaired it, but the Trouble Report and Master Sergent Anderson asked that I see if I could repair it so I did. It was not an easy fix either.
The Lt Coronal came back and whispered something to the Inspector General and General turned beet red and stormed out of the Avionics shop. The Lt. Coronal picked up the shoe box with the bad parts, the signed off (TR) Trouble Report and my log of the problems found and he also left. My Commanding Officer followed after telling me that he would see me later in his office.
We passed the Inspection with a (SIR) Significant Incident Report about what I had done. I had cost the Government some $45,000 by fixing the bugged TACAN that no one was supposed to fix.

Later I was called to the Commanding Office’s office to give him an explanation and tell him what I did and why. I told him what had happened and he broke out laughing.
The only discrepancy that we got was when IG Master Sergent Anderson took the UPS to supply power to the Aircraft; he did not have a valid UPS driver’s license and should not have been allowed to drive the unit.

Our VMA-233 had quite a reputation after that Inspector General Audit of our Squadron.

I did not have any trouble getting permission to go to any local technical schools on the Norfolk, Naval Base for the next few years. In fact, during my next 12 years, I was able to attend over 10,000 hours of technical schools while I was in the United States Marine Reserves. When I got out of the USMCR I was on my first enlistment. No one had ever spent over 14 years on a single enlistment, until I did it.