Airplane Engines 101

Spokane Turbine Center's Kodiak airplane that visited MMS Aviation July 24th and 25th is back. This time a scheduled inspection (called a phase inspection) is being performed. Because the plane is still on its nationwide tour, it wasn't feasible to take the plane back to its home base in Spokane, Washington. Three MMS mechanics are assisting STC personnel with the inspection.

Mike, an MMS Team Leader, inspects the accessory section of the Kodiak's Pratt & Whitney Canada PT6A-34 turboprop engine. It is essentially a small jet engine geared to a propeller. It produces 750 shaft horsepower and burns jet fuel. This engine whines.

Scott, an MMS Production Mechanic, helps install this Pratt & Whitney R-1830-75 engine on a Douglas DC-3 a couple years ago in Missionary Flights International's hangar in Ft. Pierce, Florida. This is a 14 cylinder reciprocating engine that burns aviation gasoline (av-gas) and produces 1350 horsepower. Pratt & Whitney hasn't built recip engines for many years. This engine rumbles.

When Rena and I were missionaries in Bolivia, I maintained a DC-3. I tell people that my Pratt & Whitneys rumble instead of whine.

Footnote to an earlier post: My brother-in-law asked why planes with turboprop engines are the future of missionary aviation. In much of the world there is very little commercial demand for av-gas. Consequently, in some places av-gas is not available and where it is available it is usually much more expensive than jet fuel. Turbo-prop engines are extremely reliable, so the safety factor is valuable to the mission aviation community as well.

Pratt & Whitney and Pratt & Whitney Canada are United Technologies companies.