The USAF’s plan to re-engine its fleet of 75 Boeing B-52H bombers has reportedly hit a funding roadblock in the US House Armed Services Committee (HASC).

The USAF has long wanted to upgrade the engines on the B-52 fleet in order to reduce maintenance overheads and improve performance on the aircraft, the youngest of which was delivered in 1962.

But US industry media is reporting that the HASC has baulked at providing US$245m (A$351m) in risk-reduction and planning funding in budget requests over the next three years until the USAF defines its specific requirements for the upgrade.

“We’re concerned that…by utilising that authority, they’re not doing their due diligence with regard to the requirements,” a committee staff member was quoted by Pentagon media on background. “We’re going to require that (the USAF) lock down the requirements, submit them to us, and let us know how they’re going to test to those requirements before they receive the full amount of funding in FY20.”

Early studies as far back as the late 1980s had looked at replacing the B-52H’s eight P&W TF33-P-3/103 turbofans, each of which produces up to 17,000lbs of thrust, with four larger 45,000lb thrust turbofans such as the P&W PW2000 or the Rolls-Royce RB211. But more recent studies are focussed on replacing them with eight business jet engines that would require fewer modification to the engine nacelles and would remain within the aircraft’s engine-out performance limitations.

Rolls-Royce has proposed its F130, the military version of the BR725 turbofan which powers the Global Express and Gulfstream G550 business jets, and their respective E-11 and C-37 military variants. Apart from being a more modern engine with an established sustainment system in place, the more fuel efficient and powerful F130 would give the re-engined B-52 much better climb performance, greater fuel efficiency, and longer range and endurance.