AOPA's 2001 Bonanza Sweepstakes - Feb. 8 Pictures and Commentary

November 11, 2009

Pictures and Commentary

Feb. 8 - During the engine upgrade in the 2001 AOPA Sweepstakes Bonanza, a 285-horsepower Teledyne Continental IO-520 engine was removed, and replaced with a 300-hp Superior Air Parts Certified Millennium IO-550 engine under a Supplemental Type Certificate (STC) held by Tornado Alley Turbos Inc.

Since the propeller that was installed on the IO-520, a McCauley 3A32C76 model, isn't approved for installation on engines that are rated for more than 285-hp, AOPA was faced with a dilemma.

We could have cleaned up and installed the C76 prop, which had been overhauled within the last year, and only had 15 hours since overhaul. While installation of this propeller is approved in the STC, it would have required the pilot to throttle back the power, which would have defeated the purpose of installing the IO-550 engine. Also, AOPA would have had to install a placard on the instrument panel directing the pilot to limit the manifold pressure and rpm. Trading in the C76 propeller for a new McCauley D3A32C409 propeller solved the problem.

The C409-style propeller is the latest example of McCauley's propeller design technology. The complete redesign features the replacement of the existing threaded blade retainer system with a threadless retainer design. This retaining system eliminates the possibility of expensive overhaul costs because of the possibility of corrosion in the retainer thread area. An improved oil-filled hub design guarantees better lubrication during cold weather, eliminates propeller hub internal corrosion, and serves to alert the pilot in case of hub problems.

Installation of the latest McCauley propeller design is another step toward AOPA's goal of featuring the latest in technology for the Sweepstakes Bonanza upgrade and refurbishment project. For more on McCauley propellers see the Web site