by

Andrew T. Bellocchio

(Advisor: Prof. Daniel Schrage, Committee Members: Prof. Dimitri Mavris, Dr. Vitali Volovoi)

Balancing Maintenance Free Operating Period Rotorcraft with Cost Capability Analysis

2:00 pm, Friday, July 28, 2017

Weber SST III

Collaborative Visualization Environment (CoVE)

ABSTRACT:

For the past 50 years, the paradigm of on-condition rotorcraft maintenance has yielded to random failures and subsequent unscheduled maintenance that regularly disrupt flight operations.  The British Ultra-Reliable Aircraft Pilot Program of the late 1990s introduced the paradigm of Maintenance Free Operating Period (MFOP) as a solution.  An MFOP aircraft is a fault tolerant, highly reliable system that minimizes disruptive failures for an extended period of operations.  After the MFOP, a single Maintenance Recovery Period (MRP) consolidates the repair of accrued faults and inspections in order to restore aircraft’s reliability for the next MFOP cycle.  An MFOP strategy provides assurance to the user that flight operations will continue without disruption for the duration of the MFOP at a given survivability rate.

The U.S. Department of Defense recently adopted MFOP as its maintenance strategy for the next generation of rotorcraft named the Future Vertical Lift (FVL) Family of Systems.  The U.S. military desires uninterrupted flight operations to enable a more expeditionary force that operates from remote, austere bases.  An initial goal of a 100-flight hour MFOP at 90% availability will be necessary to support such deployments; yet, today’s fleet has the system reliability to fly less than ten hours without significant repair at 75% availability.  Beyond FVL, the military desires to transition to near-zero maintenance with an MFOP between 480 hours and 720 hours.  The challenge presented is to achieve an order of magnitude improvement to meet the FVL target and set the conditions for near-zero maintenance while still remaining affordable.

The goal of the proposed research is to measure the balance between capability, availability, dependability, and life cycle cost of an MFOP rotorcraft.  It will utilize a Petri net-like state space in an integrated Discrete Event Simulation to model the MFOP, MRP, and their survivability as operational metrics.  The work will identify which subsystem(s) limit the MFOP of an aircraft and which components drive MRP higher.  It will explore the relationship between MFOP and MRP as well as their cost and vehicle performance implications.  It will test the hypothesis that an operational commander has some control over MFOP by varying the MRP through an aggressive lifing policy.  Ultimately, the work will demonstrate an application of Cost Capability Analysis to inform decision makers on vehicle design and technology trade decisions in a near-zero maintenance context.