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GEARED TURBO FAN JET ENGINES

Project Scope

AVISTA Software Engineers assisted with the development of all-new control software for a family of new generation Geared Turbo Fan Jet engines designed and built by a world leader in commercial jet engines.

Tightly integrated with this company’s workforce spread over three continents, AVISTA engineers developed software for Engine Ignition Start/Shutdown, Engine Control, Fuel Control, Power/Thrust Settings and Control, Cowl Anti-Ice Monitor and Activation, Air Bleed Flow Control (for anti-ice and starting), Thrust Reverser safe deployment, and Health Management and Cross Engine coordination over multiple Aircraft interfaces (ARINC). This engine made significant strides in jet engine fuel efficiency and reduced noise.

Especially challenging was the separation of requirements, model-based artifacts, and hand-code into elements that were common across all engine and airframe variants versus those that were specific to each engine variant installed on a particular manufacturer’s airframe with its communications and cockpit controls differences.

Solution

Using an Agile framework, AVISTA engineers updated and reviewed system, high, and low level software requirements (using DOORS), performed model-based design (MBD) using Simulink/Stateflow, tested those designs using both model (MIL) and software in the loop (SIL) proprietary test environments. Multi-processor control and protection logic was implemented and tested across a dual channel CAN bus fault-tolerant architecture.

Rigorous preliminary and critical design reviews for each user story were signed off with Hardware and Chief Engineers prior to each short-cycle build. Each review required successful SIL test results on the dry-bench where engine and airframe plant models interacted with the FADEC control system. As data was collected from test engine runs (wet-bench) and pre-certification test flights, AVISTA helped analyze defects and propose solutions.

Early in the program’s development, deformation of the rotor shaft due to asymmetrical cooling between successive shutdown/startup caused hardware damage. Mechanical alterations strengthened the shaft bearings. But software design changes were made to more effectively cool the engine on shutdown. The AVISTA team not only implemented the software requirements, design, and tests for the new startup/shutdown procedure, but also ensured that all platform and airframe variants were upgraded and tested with the new design.

AVISTA delivered a 3% year-over-year improvement in cost and/or efficiency (earned value) to our customer, demonstrating our commitment to quality and our customer’s needs.
Familiarity with DO-178 helped AVISTA to review and resolve thousands of documentation defects with the customer.
Over 35 engineers augmented the customer’s workforce and rapidly came up to speed in the middle of one program and also absorbed additional programs, each with its own aggressive schedule, without negatively impacting existing programs.
AVISTA engineers were given ownership of thrust and power management. Power settings determined the desired engine thrust based on pilot input, phase of flight, environmental and failure conditions in order to protect the engine against inadvertent damage.
AVISTA assisted with MBD development of an embedded model of the airflow, pressure, and temperature in a jet engine. Results of this model were used to provide more accurate diagnostics and simulate failed sensors. Correct modeling was essential to install sensors in locations providing accurate readings where a physical sensor would be impractical (such as in the combustion chamber).
AVISTA engineers were quickly recognized to be on a par with several of the customer’s Lead Engineers and were given significant responsibilities to lead their team, identify and prioritize solutions, and interface with other Lead Engineers.
Rapid changes in the customer’s priorities and workforce caused re-assignments for their Lead Engineers. In some cases, AVISTA engineers had the domain expertise and stability to train the customer’s newly-assigned Lead Engineer.