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- Analysis of the Rotorway Drive System -

Properties, Loads, Stresses, FEA, Failures

The power distribution system in the Rotorway Exec helicopter is a dynamically complex system. Unfortunately, there have been several in-flight failures of the secondary shaft in this power transmission system.

When discussing the secondary failure issue, it is helpful to have available some technical information about the RotorWay power distribution system. This section presents some background on the secondary failure problem followed by a technical analysis of the causes. This section describes the key components of the power distribution system, their mechanical and dynamic characteristics, and presents EPI's detailed dynamic analysis of the system. This analysis covers both the factory main rotor drive system (roller chain) and the main rotor drive system using the aftermarket Pro-Drive™ tooth-belt system

DRIVE SYSTEM ANALYSIS CONTENTS

 1. Secondary Failure: An Overview

ABSTRACT:
An overview of the in-flight failures of RotorWay secondary transmissions, the results, and an introduction to an analysis of the causes of the problem.

 2. Secondary Failure Database

ABSTRACT:
This document shows the extent of the problem with hard data about specific secondary failures.

 3. Digest of the Failure Analysis

ABSTRACT:
A condensation of the detailed analysis presented in the remainder of this section.

 4. Analysis Model of the Drive System

ABSTRACT:
Description of the system model used to analyze the dynamic properties and vibration modes of the main rotor drive system.

 5. System Excitation from the Engine

ABSTRACT:
A description of the engine characteristics which produce the very high torsional excitation which is seen throughout the rotor drive system.

 6. System Properties of the Main V-Belt Drive

ABSTRACT:
A description of the power transmission properties of the main V-belt drive, and the loads this drive generates in the system.

 7. System Properties of the Main Rotor Chain Drive

ABSTRACT:
A description of the power transmission properties of the main rotor chain drive, and the loads this drive generates in the system .

 8. System Properties of the ProDrive™ Belt System

ABSTRACT:
A description of the power transmission properties of the ProDrive main rotor toothbelt drive, and the loads this drive generates in the system.

 9. Very Large Loads from ProDrive™ System

ABSTRACT:
Explanation with numbers and pictures of the three reasons the ProDrive belt system overloads the RotorWay secondary shaft.

10. Drive System Dynamic Properties

ABSTRACT:
This document shows the level of engine excitation in the drive system, and derives the inertias and torsional rates used in the dynamic analysis.

11. Drive System Vibration Modes

ABSTRACT:
This document presents the determination of the 4-degrees-of-freedom Main Rotor Drive System vibration modes.

12. Metallurgy of the Factory Secondary

ABSTRACT:
Analysis of the metallurgy of the factory secondary, with strength, fatigue and hardness data.

13. Loads on the Secondary Shaft

ABSTRACT:
This document shows the magnitudes and directions of the various loads the Secondary Shaft carries, and the critical stresses they generate.

14. FEA of Factory 35mm Shaft

ABSTRACT:
Stress analysis of the factory 35mm secondary under various load scenarios.

15. Fatigue Failure of the Shaft

ABSTRACT:
This document explains why the shafts are experiencing fatigue failures, and has some interesting pictures of some failed sections.

16. Secondary Bearing Issues

ABSTRACT:
This document describes problems with excessive load and reduced life of both secondary shaft bearings.

17. Gates Toothbelt Issues

ABSTRACT:
Clarification of some of the myths, rumors, claims, counterclaims and just plain hype regarding the use of the Gates toothbelt for a main rotor drive.

18. Autorotation Clutch Issues

ABSTRACT:
Description of the operation and construction (with pictures) of the RotorWay autorotation clutch, with an explanation of its main deficiency.

19. Engine Concerns

ABSTRACT:
A brief discussion of several concerns about the RotorWay piston engine (not really related to the main drive system).

20. EPI Secondary Upgrade Status

ABSTRACT:
This document describes the inspection program and results of inspections, as well as a few problems encountered by users of the EPI secondary transmission upgrade system.
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