Recip Technology: Did I Hear a Radial?

Last August while fishing in Katmai National Park, Alaska, two brightly painted de Havilland DHC-2 Beavers flew over and landed on nearby Naknek Lake. They taxied up and I heard those beautiful R-985s clatter to a stop. In about 15 minutes the bush pilots had off loaded the tourist, repositioned the Beavers and were taxiing out for a takeoff.

As I watched them lift off some maintenance thoughts came to mind. I knew that Pratt & Whitney Canada (P&WC) had stopped producing the R-985s in the early 1950s, so who maintains and overhauls those old workhorses? What are the specifications now and where do they get parts? If someone was operating aircraft powered by radial engines then there were mechanics out there trying to find an oil leak, measuring cylinder wear, or timing a magneto.

The operator

Some of those AMTs work for Rust’s Flying Service in Anchorage, AK. Its fleet of aircraft includes five DHC-2 Beavers used by experienced bush pilots to take clients bear watching, on fishing and hunting trips, and to fly-in lodges. I contacted Colin Rusts, owner and operator, and asked if he would like to talk about radial engines. I quickly learned that anyone that has any experience with these engines loves to talk about them. Colin says that the Beavers powered by R-985s were ideally suited for the Alaskan environment and the day charter business. They are safe and dependable, with very few maintenance problems.

He says that “when Pratt & Whitney designed these engines, they got it right the first time.” Rust’s has a staff of five to six experienced A&Ps that maintain its fleet of aircraft. “They like to maintain the R-985s because they are classics. Up here, a lot of nostalgia and prestige are associated with maintaining bush planes and these engines. They are like Harley-Davidsons. Our maintenance guys take good care of the engines and are especially careful with oil leaks. We fly into the National Parks and other environmentally sensitive areas where any fuel or oil contamination is forbidden. We will continue operating the R-985s as long as we can get parts, low lead 100 octane aviation gas, and the engines overhauled.”

I contacted P&WC and asked about engine overhauls. I was surprised to find that Pratt & Whitney R-985 and R-1340 radial engines are still performing vital services in the agriculture industry, backcountry charters, and light freight forwarding. They are mounted on aircraft flown by the military, state, and local agencies and hobbyists that you see at Oshkosh AirVenture. P&WC stopped supporting the R-985 in the late ‘50s and the R-1340 in the late ‘60s however it recommends Covington Aircraft in Okmulgee, OK, for maintenance, repair, and overhaul (MRO) work.

Covington Aircraft, the MRO

The Abbott family operates Covington Aircraft with a strong personal faith and through the four core values of integrity, dependability, quality service, and affordability.

Covington Aircraft’s Radial Engine Division is the largest R-985 and R-1340 overhaul facility in the world. It has about 30 employees that include A&Ps, engine overhaul technicians, welders, machinists, NDT and quality control inspectors, and supply specialists that perform all overhaul functions except chrome plating. I spoke to Rob Seeman and Blaine Abbott. Blaine manages the QA function and is the company historian and resident expert on most things R-985 and R-1340.

I asked why radial engines? “If you recall, in the mid ‘70s before UPS and FedEx, there was a good number of small freight and agribusiness operators flying aircraft with radial engines. Servicing this diverse customer base was good business.”

Covington has been doing this for about 40 years and I was curious as to what had changed with the OEM, the customers, and the radials. They said that the FAA certifications were easy to get and the OEM authorization had developed over time. The staff at Covington is very proud that they are a P&WC certified distributor and designated overhaul facility (DDOF).

That expertise and customer care attitude is valued by Covington. It has very low turnover and its story is very similar to Rust’s Flying Service up in Anchorage. Some mechanics really like to work on radial engines. Blaine Abbott says, “We have a great in-house training program. Usually a mechanic will start out in teardown and work through our OJT program. We encourage our mechanics to get their A&P or repairman certificates. We have mechanics trained and developed with the skills and confidence to go out in the field and work at the customer’s location.”

Overhaul customers

They explained that in the past 40 years the customer base has flipped because most of the light freight haulers are gone. Now about 80 percent of their customers are in the agribusiness flying AgCats, Weatherly, Air Tractors, and Thrushes. Another 15 percent are in the air taxi business and the rest are hobby customers. They generally fly Beavers, Otters, Harvards, SNJs, Stearmans, BT 13s, and AT6s.

Seeman says, “Our radial overhaul business is still pretty good. Covington is now a global company and has a worldwide customer base. About 40 percent of the business is export. We estimate that about 8,000 to 10,000 R-985s and R-1340s are still operating. These engines can generally operate between 1,200-1,600 hours of time between overhaul (TBO). Radials come in for overhaul because of high oil consumption, propeller strikes, Airworthiness Directive 68-09-01 compliance, or they have timed out.” The AD must be accomplished at 1,200 or 1,600 hours depending on propeller installation. To accomplish this, the engine must be disassembled to the point it is more economical to overhaul than to just comply with AD 68-09-01.

Tools, fixtures, and parts

I asked about the production side of the overhaul process, especially about their tools and fixtures and parts inventory. Seeman says that they are “currently overhauling around 180 R-985s and R-1340s a year. If we have the parts on hand we can overhaul a radial in about 30 days.”

Abbott says that “a huge number of radials were produced during the war years. About 39,000 R-985 Wasp Juniors were produced between 1929 and 1953, and 35,000 R-1340 Wasps were produced between 1925 and 1960. Many of these engines and parts were offered on lend lease agreements to other countries. Also, a lot of surplus left the United States and went to third-world countries. Parts suppliers have been buying up that surplus from those countries and putting the inventory back on the U.S. market.

“There are parts manufacturing approval (PMA) businesses that are manufacturing radial engine parts and accessories. Covington is a (PMA) holder and manufactures gaskets and seals for the Wasps. We bought many of our tools and overhaul equipment on the surplus market. Those we could not get, we redesigned and built better ones.”

Future of the radial engines

I asked Seeman and Abbott for an opinion on the future of the R-985 and R-1340 radial engines. They say that “for engines designed in 1920s, they are still very reliable, probably more so today. Improvements in the design and materials for seals and gaskets have reduced oil leaks and dried the engine up. As for longevity, it is all about economics. The agribusiness operators will fly these engines as long as it is profitable to do so.”

Pratt & Whitney no longer produces its famous Wasp engines but there are at least five companies building radials today. Rotec Engineering Pty. Ltd. in Victoria, Australia, is producing the Rotec R2800 (a 110-horsepower seven-cylinder engine) and the R3600 (a 150-horsepower nine-cylinder engine). And, Verner Motors in the Czech Republic is building a modern five-cylinder radial.

It appears that these remarkable engines will be around for some time. There are operators using them, hobbyists flying them, and mechanics taking pride in maintaining them. This is very good news for the romantics among us. There are some sounds that we hope never fade away, like birds singing in the spring, straight pipe Harleys, 440 hemis, and radials turning over on a cold morning. 


Charles Chandler is an A&P based in Michigan. He received his training from the Spartan College of Aeronautics.