TECHNOLOGY AREAS: Air Platform

ACQUISITION PROGRAM: PMA-275, V-22 Tiltrotor Aircraft

OBJECTIVE: Establish an innovative approach to develop a universal gearbox load simulation software concept for helicopter drive systems and engine gearboxes.

DESCRIPTION: Currently the Navy, Marines, Army, and Air Force face situations where there is the need to identify new retirement times for aircraft gearbox components due to changes to the aircraft mission and/or component configuration or condition. It can often take months to acquire these calculations from the original engine manufacturer (OEM). There can also be additional cost expenses and delays to a program. A universal software concept is required that is capable of estimating loads and life of components (e.g., recommended removal time) based on the users� drive system design parameters (dimension, weight, diameter, number of teeth, material, loads, gear ratios, etc). The software concept should also provide estimated values depending on the type of mission load spectrum. Areas for exploration for this tool include fringe plots for effects and factors for sliding, heating, cooling, oil-film/viscosity loading, dynamic contact patterns, misalignments, and surface finishes. These areas are currently not addressed in aircraft drive system life analysis due to the complexity of the analysis.

PHASE I: Determine the feasibility of implementing a software component life load prediction tool for drive systems. Identify and define required helicopter transmission parameters to develop user specification entry data or data requirements.

PHASE II: Develop, construct and demonstrate an operational prototype of the drive component life load software. Develop viable demonstration cases with collaboration from the government or private sector.

PHASE III: Work with OEM(s) to provide end user specified software packages and software support.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The commercial sector would benefit from a prognostic software prediction tool for gearbox loads by reducing unscheduled maintenance and unnecessary transmission removals. This in turn, would provide a significant cost savings benefit by increasing gearbox time-on-wing.

REFERENCES:
1. Johnson, RB; Cox TL. (1974). "Helicopter Drive System Load Analysis [Final Report]." (Report No. AD-775858; USAAMRDL-TR-73-105).

2. Bartelmus W. (Sep 2001). "Mathematical Modelling and Computer Simulations as an Aid to Gearbox Diagnostics." Mechanical Systems and Signal Processing, Volume 15, Issue 5, 855-871.

3. Place, C.S., Strutt J.E., Allsopp K, Irving P.E. & Trille C. (Mar-Apr 1999) "Reliability prediction of helicopter transmission systems using stress-strength interference with underlying damage accumulation." Quality and Reliability Engineering International, Volume 15, Issue 2, 69-78.

KEYWORDS: Drive System Loads; Helicopter; Gearboxes; Software Prediction; Gears; Bearing; Shaft Loads

** TOPIC AUTHOR (TPOC) **

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