The KA-6D was a tanker version of the Intruder, created by conversion of existing Intruder airframes.
Grumman had tried out a buddy midair refueling pod underneath a conventional A-6A (BuNo 147865). In addition, Grumman fitted an internal refueling package into BuNo 149937. But these projects never proceeded any further because of a lack of any perceived need for a tanker Intruder.
However, in 1968 the Navy changed its mind and Grumman was finally given authority to proceed with a tanker version, designated KA-6D. The first KA-6D was obtained by modifying BuNo 151582. It first flew on April 16, 1970, crewed by Chuck Sewell and D. R. Cooke.
The KA-6D was fitted with an internal hose-and-reel refueling package, with the drogue fairing protruding from underneath the rear fuselage. It could also carry a D-704 refueling pod on the fuselage centerline. The D-704 acted as a backup to the internal refueling system, and provided its own power via a ram air turbine mounted on the front. The radar and most of the DIANE equipment was removed, but the KA-6D still retained a visual bombing capability (which was seldom exercised). There were only minimal controls provided for the second crew member, whose duties were now navigation and the monitoring of the refueling operation.
A total of 90 KA-6Ds were produced by modifying existing Intruder airframes. Although all of the planes used airframes that were originally built as A-6As, 12 of them had previously been upgraded to A-6E standards. When rebuilt from A-6As, the KA-6Ds received all new fuel tanks, with two fuselage bulkheads being replaced. There was extensive rework of the outer wing panels. The aircraft was completely rewired. The DIANE) system was taken out, The Omega global inertial navigation system was fitted, with the entire suite being controlled by an ASN-41 navigational computer. For typical missions, the KA-6D caries four fuel tanks on the wing pylons. The D-704 is sometimes carried as a backup to the primary hose-drum unit, or as a means of ferrying the pod to other units.
The first deployable Intruder squadron to receive the KA-6D was VA-176, which received its first tankers on September 25, 1970. Each deployed Intruder squadron typically had 3 or 4 KA-6Ds assigned to it for the tanker mission.
There was always the ever-present danger that the refuelling hose could become stuck in the deployed position after a refuelling operation and could not be reeled in. While the refueling hose is deployed, the carrier arrester hook could not be extended and it would be impossible to land on a carrier. The unfortunate aircraft would have to find a land base very quickly or the crew would have to eject. In order to prevent this from happening, there was an emergency explosive cutter which could sever the hose and allow it to drop into the sea.
The KA-6D theoretically could be used in the day/visual bombing role, but it apparently never was, with the standard load-out being four fuel tanks. Because it was based on a tactical aircraft platform, the KA-6D provided a capability for mission tanking -- the ability to keep up with strike packages and refuel them in the course of a mission.
149475/149486 Grumman A-6A Intruder 149482, 149484, 149485, 149486 modified as KA-6D. (4) 149935/149958 Grumman A-6A Intruder 149936, 149937, 144940, 144942, 144945, 149951, 149952, 149954 modified as KA-6D. (8) 151558/151612 Grumman A-6A Intruder 151566, 151568, 151570, 151572, 151575, 151576, 151579/151583, 151589 modified as KA-6D. (12) 151780/151827 Grumman A-6A Intruder 151783, 151787, 151789, 151791/151793, 151795, 151796, 151801, 151806, 151808/151810, 151813, 151814, 151818, 151819, 151821, 151823/151827 modified as KA-6D. (23) 152583/152646 Grumman A-6A Intruder 152587, 152590, 152592, 152597, 152598, 152606, 152611, 152618, 152619, 152624, 152626, 152628, 152632, 152637 converted as KA-6D tanker. (14) 152891/152954 Grumman A-6A Intruder 152892/152894, 152896, 152906, 152910, 152911, 152913, 152914, 152919/152921, 152927, 152934, 152939 converted as KA-6D tanker (15) 154124/154171 Grumman A-6A Intruder 154133, 154147, 154154 converted as KA-6D tanker (3) 155581/155721 Grumman A-6A Intruder 155582/155584, 155588, 155597, 155598, 155604,155619, 155638, 155686, and 155691 converted as KA-6D tanker. (11)