Secondary Engine for Compensating Main Engine Power Losses
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Solution Overview
Problem
The high direct maintenance costs and downtime of rotary wing aircraft engines due to overdimensioning for emergency power ratings and degradation over time, which leads to increased maintenance operations and reduced performance.
Innovation Solution
A power plant configuration with two main engines and a secondary engine, allowing the secondary engine to deliver two distinct power levels to compensate for main engine power losses, ensuring continuous safe flight without immediate maintenance, thereby reducing maintenance costs and extending aircraft availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If engines are overdimensioned to provide emergency power ratings, then reliability is improved, but direct maintenance costs increase and engine degradation accelerates
Solution Approach 1:
The power plant is segmented into main engines and a secondary engine with distinct functions. The secondary engine specifically handles emergency power compensation, allowing the main engines to operate at optimal ratings without the need to be overdimensioned for emergency scenarios. This segmentation resolves the contradiction by separating the emergency power function from the main propulsion function.
Solution Approach 2:
The secondary engine acts as an intermediary component that compensates for power losses from main engines during emergencies. Instead of sizing main engines for emergency conditions, the secondary engine mediates the power deficit, allowing main engines to be optimally sized for normal operation while maintaining emergency capability.
2Reliability
If engines are overdimensioned for emergency ratings, then emergency power capability is improved, but engine lifetime decreases due to degradation
Solution Approach 1:
The power generation function is segmented between main engines (for normal operation) and a secondary engine (for emergency compensation). This allows main engines to operate within their optimal lifetime parameters while the secondary engine handles the stress of emergency power delivery, preserving main engine lifetime.
Solution Approach 2:
The secondary engine is designed as a smaller, less critical component that can be replaced more easily than main engines. It absorbs the wear and degradation from emergency operations, serving as a protective sacrificial element that preserves the lifetime of the more valuable main engines.
3Reliability
If maintenance operations are performed frequently to address engine degradation, then reliability is maintained, but aircraft availability decreases
Solution Approach 1:
The secondary engine is pre-configured and pre-positioned to immediately compensate for main engine power losses. This preliminary arrangement eliminates the need for frequent maintenance interruptions, as the secondary engine provides continuous backup capability without requiring reactive maintenance operations.
Solution Approach 2:
The secondary engine enables continuous operation of the aircraft by compensating for main engine degradation in real-time. This maintains reliable power output without interrupting aircraft availability, as the secondary engine continuously makes up for power losses rather than requiring shutdowns for maintenance.
Data Source
AI summary
A method of managing a power plant for a rotary wing aircraft, said power plant comprising two main engines, a secondary engine, and a main power transmission gearbox (MGB). Said main and secondary engines mechanically driving said MGB so as to rotate a main rotor of said aircraft. Said secondary engine delivers two distinct mechanical power levels so that said main and secondary engines together deliver sufficient mechanical power to enable said aircraft to fly, firstly a first secondary mechanical power MPS1 and secondly a second secondary mechanical power MPS2 suitable for compensating for a loss of main mechanical power from at least one main engine.