The Republic of Singapore Air Force (RSAF) has concluded its Boeing KC-135R Stratotanker operations, ending 21 years of the type’s service. The 112 Squadron conducted its last flight on June 26, according to sources familiar with the platform.

The end of KC-135R operations comes less than a week after the squadron’s third Airbus A330 Multi Role Tanker Transport (MRTT) was delivered from Spain on June 20. Mindef (Singapore’s ministry of defense) had said that the operational introduction of the A330 MRTT is on track and progressing well, and the KC-135R will be progressively drawn down as the A330 MRTT is brought into full service.

Singapore acquired four ex-USAF KC-135Rs in 1996, with the oldest airframe built in 1959. They were heavily refurbished with modernized cockpits, chaff/flare dispensers, and multi-point refueling system (MPRS) for drogue and probe refueling. The latter was especially sought after when an RSAF KC-135R was deployed to the Middle East in support of the coalition force efforts in defeating ISIS, where the MPRS was able to refuel all coalition aircraft regardless of receiving methods.

The RSAF opted for six MRTTs in 2014, with the first aircraft delivered on August 14, 2018. The retirement of the KC-135R also suggests that the new tanker has achieved initial operational capability (IOC) and the RSAF has fully overcome tanking issues between the MRTT and F-15. It had been reported that the probe would often be in close contact with the F-15’s canopy when executing a turn while refueling.  

Currently based at Changi Airbase (East), Singapore’s MRTTs are in a two-class configuration seating 266 passengers, while the center overhead compartments are fitted with life-support attachments for when the aircraft is configured for medevac operations.

Meanwhile, as part of the Republic of Singapore Air Force’s effort to leverage new technologies to maximize manpower and airpower generation, its automatic aircraft visual inspection system is now at an advanced stage of trials and linked to a fleet management system.

Unveiled in March 2017, the automatic inspection system uses high-resolution camera systems with artificial intelligence capability to detect, identify, and classify defects and abnormalities on an aircraft surface. Currently, manual inspections take 30 minutes or more, but the RSAF hopes the camera system can do so in minutes. Eight cameras are mounted on a hangar ceiling, which will point out 14 types of defects on a 3D model on the computer interface. These defects include loose or missing screws, fluid leaks, and cracks. The RSAF, in collaboration with the local defense technology community—which includes the Agency for Science, Technology and Research’s Institute for Infocomm Research (A*STAR I2R) and Defence Science and Technology Agency (DSTA)—has fed the computer thousands of images, enabling it to machine learn and recognize defects accurately.

At the same time, an unmanned ground vehicle (UGV) is under development and would have a similar camera system to inspect the underside of the aircraft. The RSAF is now testing the UGV’s ability to avoid obstacles and navigate around the aircraft safely.

Any detected defects would be fed to a fleet management system (FMS) to give the maintenance controller an overview of the serviceability of the aircraft fleet. The FMS also has an optimizer engine that will recommend the best set of crew to service an aircraft and the optimum aircraft for subsequent sorties. The trial is currently being carried out on the Lockheed Martin F-16C/D at Tengah Airbase, before being expanded to other airbases and platforms.