EMC War Stories

It was difficult to pick one EMC war story out of literally hundreds. But this story has a very interesting twist. It relates to solving a problem on the Grumman-built US Navy E-2A aircraft that hampered its early flight developmental testing at Grumman’s Bethpage, Long Island, New York airport. The aircraft’s Avionics Flight Test Engineer, Bill, reported that the problem was caused by radio interference in the LF/ADF (Low Frequency/Automatic Direction Finder) radio. This interference limited aircraft flights to within five miles of the airport; thus, precluding flights at the longer distances needed for developmental testing. (The maximum range of that radio is about 100 miles.). Furthermore, Bill reported that the EMI engineers didn’t know how to solve the problem. Subsequently, I discovered his bias against EMI personnel.
Summarily, in late 1960, several months after hiring into Grumman to work on the A-6A aircraft, my supervisor directed me to investigate and develop a solution for the reported problem. A flight test was scheduled on “Christmas Bonus Day.” I appeared at the flight ready room, met Bill, and asked “What now?”
He said, “Harness up.”
I replied, “Show me how, and what do I do if we have to use the parachute?” (This is part of the harness for those who are not familiar.)
He said, “You mean you haven’t been to school and been certified to fly?”
I noticed that he had a wry smile on his face and he said, “You’re going to fly any way.”
So, he harnessed me up and as we walked towards the aircraft Bill briefed me on aircraft ejection procedures.
The E-2A aircraft has a left and right engine, a forward compartment for the pilot and co-pilot, and an aft compartment for three radar operational personnel. On this flight I occupied the rear most seat and the flight test engineer was seated adjacently. The E-2A took off and I completed my test. Then the pilot announced that we had time to conduct “a fish-tail experiment.” (Fish-tailing causes aircraft movement from side to side.) Since maximum movement would be experienced by the occupant of the rearmost seat, the pilot requested that I report my observations as he stopped, in turn, the left and right engines. In so doing, my mind became preoccupied with “If we ditch, do I eject or not? Who’s going to pick up my bonus check?” We didn’t ditch, returned to the airport and assembled in the debrief room to audio tape our observations. I reported that my test results revealed that the limited range of the LF/ADF radio was not due to interference but to inadequate antenna performance. The flight test engineer reported that the test proves that it was an interference problem. We were back to square one. The controversy persisted until I convinced the Chief E-2A Test Pilot, Tommy, to make a flight with a “jury-rigged” antenna installed per my recommendation about six inches below the aircraft’s fuselage.
Several days later, Tommy took off with the jury-rigged antenna while the ground crew and I monitored the flight. Tommy flew out to five miles, then to ten miles and then finally reported that he is over 100 miles away. Tommy returned, landed and proceeded to say, “If anybody tries to take that antenna off, I will exercise my prerogative.”
Everybody knew what that meant. As did each of the chief test pilots of Grumman aircraft: he is authorized to phone the CEO. Thus, the developmental flight test continued with a rigged antenna.
Meanwhile, the E-2A, Antenna, and Avionics Flight engineers were still arguing that it was not an antenna problem. Their basis was that I had moved the antenna away from the interference source by bringing it outside the airplane.
I said, “You are wrong and the E-2A EMC Group will perform testing to so prove.”
Meanwhile, my Section Chief directed me to develop a test plan and a mathematical model to prove my contention, as well as to oversee the testing and lead discussions on resolving the conflicting views. In so doing, I read the antenna installation manual that recommended a minimum fuselage aperture size. However, the actual size was well below the minimum.
My discussions with Bill, the antenna engineer, revealed that he had approved downsizing the aperture because the Structural Engineering department had so requested and that the antenna manufacturer had so approved. I told Bill about the upcoming antenna test whose purpose was to measure antenna performance.
That testing was performed, which required monitoring the signal levels received by the antenna while it was lowered, one inch at a time, from its installed location inside the fuselage until it was six inches below the fuselage. The test results validated the mathematical model that showed that the received signal would increase and peak at about four inches below the fuselage.
After Bill reviewed that data, he endorsed a permanent antenna in a radome below the aircraft’s fuselage.
Epilogue: After my “Christmas Bonus Day” flight, I collected my bonus check and on my next pay cycle, I noticed that my pay had been increased. Subsequently, I was assigned as the E-2A EMC Group Leader. To this day, 47 years later, that antenna sits two inches below the fuselage of the latest version of the E-2 aircraft.
Editor’s Note: The author of last issue’s “War Story”, Vincent Mancino, was incorrectly identified in the photo accompanying the story. EMC Founders Vincent Mancino (left) and Anthony Zimbalatti (right) are correctly shown above. EMC