GTC upgrade to APU in C-130 Technical Posted July 30, 2017 On 4/26/2017 at 8:31 AM, Spectre623 said: GTC oil tank goes from inside cargo cmpt. to inside WW pod on APU. Bill Bill. Interesting to note that the APU could be run inflight (except on commercial Hercs), but not serviced inflight while the GTC could be serviced inflight but not run inflight. Anyone else see the irony here? Don R.