An Evaluation of the Design Requirements of the H-1 Upgrades Helicopter Blade Fold Racks

The United States Marine Corps contracted Bell Helicopter Textron Inc. (BHTI) to develop and field new versions of the aging UH-1N and AH-1W helicopters. As part of the development effort of the H-1 Upgrades, BHTI was tasked with development of a folding rotor system and the associated equipment necessary to support main rotor folding operations. The blade fold equipment (BFE) was constrained throughout the development process by a list of conflicting requirements. The requirements for commonality, versatility, simplicity, light weight, rapid application, and durability, while each was generally reasonable, could not be satisfied with one set of equipment. The resulting BFE was ineffective for everyday use.

The purpose of this thesis was to evaluate the design requirements of the BFE, specifically the blade fold racks. An investigation of the source of requirements was conducted, followed by interviews with system experts and end users. Additional data were gathered during the program-sponsored test events from January through May 2005.

In order to develop a suitable and effective set of BFE, the H-1 Upgrades program should reduce the set of design requirements on the new blade fold racks, specifically:

1. Modify the H-1 Upgrades aircraft to incorporate an automatic folding rotor system or a blade indexing motor.

2. Redesign the blade fold racks for a reduced set of configurations and load conditions.

3. Consider a simple, one piece, clamping blade fold rack.