WestJet Set To Debut 737 Drag-Reduction Kit

ADL 737 kit
Credit: ADL

Canadian operator WestJet is installing a production standard Aero Design Labs (ADL) drag reduction kit on a Boeing 737-700 and is expected to debut the fuel saving modification in service over the coming weeks.

The Calgary-based airline was the original launch customer for the kit but required Transport Canada approval based on the FAA supplemental type certificate (STC) before entry-into-service. The operator is therefore already familiar with the aerodynamic drag reduction system (ADRS) modification package, having provided an aircraft for baseline flight tests and the original STC, which was awarded to Texas-based ADL earlier in 2022.

The airline, which presently operates 41 737-700s on a wide range of routes including long-haul transatlantic flights, is expected to fly the first modified aircraft for up to 90 days to validate actual fuel savings in the WestJet network. ADL expects the lightweight kit to result in fuel burn reductions of at least 1.5% on the 737-700, with larger improvements anticipated when kits are flown by other operators on the larger -800/900.

WestJet’s move comes as Southwest Airlines fits ADL kits to four additional 737-700s following the start of the first revenue flights with the first modified aircraft earlier in March. The last of the total of five kits acquired for testing will be installed by the end of April says ADL. The company anticipates Southwest will trial the kit for 60 days once all the aircraft are modified and in service.

In addition to the 737-700, tests of the ADL kit on the 737-800 and -900 are expected to get underway later in 2023 following the signing of a memorandum of understanding in November 2022 with Delta Air Lines. Overall, ADL is optimistic of placing the ADRS kit with a large percentage of the 737 Next Generation in-service fleet which, according to Aviation Week Network’s Fleet Discovery, currently includes more than 5,200 aircraft. 

The baseline ADRS kit consists of modifications to address areas of interference and parasitic drag around the fuselage that have never previously been tackled or only partially treated over the life of the aircraft. In the case of the 737-700/800 and -900, the ADRS package includes a revised wing-to-body aft fairing, modified flap track fairing tips, updated wheel well fairings, revised aerodynamics around the environmental control system pack ram air exit duct, and several aft-mounted vortex generators and aerodynamic fences.

Beyond the 737, ADL is targeting potential drag kits for the Airbus A320/321 and 767, studies on which will be undertaken through 2024. 

Guy Norris

Guy is a Senior Editor for Aviation Week, covering technology and propulsion. He is based in Colorado Springs.