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Gregory F. Heath is a mechanical engineer whose documented research includes rotorcraft transmissions and face gear technology. His2010 author biography describes him as an associate technical fellow at Boeing Rotorcraft-Mesa and a technical integrator for an advanced rotorcraft-drive program.^[ref]

Heath coauthored Development of Face Gear Technology for Industrial and Aerospace Power Transmission by Gregory F. Heath and others with Robert R. Filler and Jie Tan. Their2002 report documents a250-horsepower proof-of-concept split-torque transmission using concentric face gears. The tests examined whether floating input pinions could divide the load nearly evenly between parallel transmission paths.^[ref]

The mechanical question is more demanding than obtaining the desired gear ratio. If two parallel paths have unequal geometry or effective stiffness, one can carry more torque than intended. In an ideal equal-speed example, dividing a100N·m input into50N·m in each path also divides input power equally. A60/40N·m split preserves the total transmitted torque but raises the larger path's load20% above the intended50N·m share. A floating pinion supplies freedom intended to improve load balance; the report's apparatus and measurements tested how that mechanism behaved in a manufactured transmission.

Heath also coauthored the later gear-pitting detection study with Paula J. Dempsey, David G. Lewicki and Perumal Shanthakumaran, linking transmission development with experimental assessment of damage indicators.^[ref]

Jie Tan coauthored Development of Face Gear Technology for Industrial and Aerospace Power Transmission by Gregory F. Heath and others with Gregory F. Heath and Robert R. Filler. Its2002 title page identifies Tan with The Boeing Company in Mesa, Arizona. The work investigated concentric face gears and floating pinions as a means of distributing transmitted torque between parallel paths.^[ref]

The report is useful because its apparatus revealed that different load divisions in one split-torque transmission need not agree. While input-pinion mesh division was close to48/52, the idlers were reported near57/43. The authors related the idler imbalance to how backlash had been set using strain indications, and discussed the limitations of inferring the split from those indications alone.^[ref]

In an illustrative100-unit load normalization, a57-unit path is14% above the intended50-unit equal share. A geometric gear ratio can remain correct despite that unequal internal loading. Tan's coauthored study therefore provides a concrete connection between transmission geometry, adjustment and experimentally inferred forces, rather than treating the desired speed ratio as a complete description of mechanical performance.

Robert R. Filler is a coauthor of experimental mechanical-engineering work on face gear transmissions. The2002 report with Gregory F. Heath and Jie Tan identifies all three with The Boeing Company in Mesa, Arizona. Their report documents design, manufacture and testing of a scaled250-horsepower proof-of-concept split-torque transmission.^[ref]

The experiment made load balance measurable. The input pinions were slow-rolled under torque supplied through weights, pulleys and cables, while tooth-root strain gauges recorded deformation associated with load. Measurement calibration was needed to convert those indications into an estimate of the torque division. The reported full two-pinion/two-idler configuration gave approximately48% and52% at the upper and lower input-pinion meshes.^[ref]

For an illustrative normalization to100N·m total input torque, those fractions correspond to48 and52N·m. The larger branch is4% above an ideal50N·m equal share, even though the two branches differ by4N·m. The distinction matters when comparing a measured torque split with the load intended for each path. Filler's documented contribution is as a coauthor of the experimental transmission study; the result depends on the complete tested arrangement.