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Where in the Hell are we??.....Where's up??.....Where's North??....Where's the Club??.... This is one of a thousand stories that could be told of the avionics issues relating to the early A-6As. Maintenance Control was more of a euphemism than fact, but we got the job done. VMA(AW)-242 deployed to Da Nang in 1966 as the first USMC A-6 Squadron in-country. Leading the deployment was a forward cadre sent on ahead to set up the Electronic Systems Maintenance vans right behind the 242 hanger, and where all of the avionics test and repair took place on black boxes pulled at the flight line. It was October, the weather was less than optimal (like that's a revelation) and we soon discovered that the Inertial Navigation System (INS) Platform Test Station may be in trouble. The Platform is the heart of the INS which houses the gyros and accelerometers used to measure angular rate and acceleration, as well as gimbal mechanisms to keep the internal workings stable during any aircraft maneuver. (Nerd Alert - I warned you) Anyway, to properly calibrate the Platform, the Test Stand must know it's position (Lat / Long) precisely and it must be aligned to True North. Now there's the rub! The plot thickens. Da Nang, RVN, is just above the equator at about 16o N latitude which put the North Star somewhere around nose high. So what you say! Well, without a good "Polaris Shoot", there is no reference to True North and hence no calibration of Inertial Platforms. For several nights we went out with trusty theodolite and attempted to find the North Star, but to no avail. At ground level it was constantly shrouded in haze/clouds just above the horizon. The only Time Tables we had were for Polaris and we had no other celestial charts, so we couldn't use another star, dust off the Trig tables and get a bearing that way either. So, what to do?? As luck would have it, we had the smartest avionics trained Marine available in the person of Gunny Tom Verhovchek from H&MS who suggested that we take the Platform Test Stand (Humongous 3 Axis steel monster), manually move it around to approximately north and then use the gyrocompassing capabilities of every Inertial Platform to "find north" for us. And, since the stand was not perfectly level, which was another criteria for alignment and calibration, we used the accelerometers within the Platform in two axes to allow a manual leveling of the stand each time a Platform was tested. Tedious is too kind a description, but Tom conceived of the idea, I believe, while we were still at Cherry Point prior to deployment and it worked. The small army of Contractor Reps who deployed with us included Litton Guidance & Control Systems guys who accepted the new procedures (Like they had a choice), and onward we went. The new procedure, unfortunately took us twice as long to calibrate each Platform, but at least we had a solution. The only way this scheme wouldn't work was if all you had was a truly broken Platform and no other to help align the Test Stand. That scenario never occurred as we were, unfortunately, rich in Platforms needing to be re-calibrated all the time. We no sooner got the Inertial Platform Test Station up and running when the aircrews transpac'd the birds in and work began in earnest. The Inertial System on the A-6A was very touchy and somewhat unreliable, and Platforms were always in for repair. I can only remember a few times when I actually had to replace a gyro, accelerometer or other component. It was mostly a task of getting the calibration to stay put for more than a few missions and not drift off. Gyro replacement was not authorized at the Intermediate Maintenance Level, but we did a few anyway rather than lose the Platforms to the depot and risk never getting them back. Inertially speaking, things were going relatively smooth until about June of 1967 when the Inertial Platform Test Station went down due to a blown transformer. There were no replacement transformers in-country and Platforms were backing up to a critical level. What now kimasabe?? Ole Gunny Verhovcheck and I loaded two boxes containing some 8 Platforms onto a C-130 and went to Cubi Point and used the swabbies' Test Station. The Navy was less than thrilled and we had to work around their schedules. They had their own problems. We could only work on/calibrate one Platform a day in the early morning, and not all days were available to us. Being creative and resourceful, we discovered that the golf course and Olongapo City needed modifications and proceeded along those lines during "off hours". It was back to Da Nang after a few weeks and the rest of the tour was electronically uneventful. The fact remains that all parts of the Marine Corps have worked around problems no matter what type or wherever found. "Creative" acquisitions and the use of resources to their fullest has always been our trademark. There were many stories like this where necessity and innovation created solutions to problems which went outside the book and SOP to get the mission done. It was an interesting, complex time. Semper Fi. Bob "Gorilla" Guerra FILE ARCHIVED ON 2003.06.23 AND RETRIEVED FROM THE INTERNET ARCHIVE ON 2005.11.21 BY INTERNET ARCHIVE WAYBACK MACHINES. ONLY NON-COPYRIGHTED MATERIAL IS INCLUDED. |
