Comar Designs - Airbus A220 PDU Test Equipment

By Comar Engineering Services
schedule11th Apr 24

Our latest design of a test rig for production acceptance testing (PAT) of the aircraft power drive unit (PDU)for the Airbus A220 might never have occurred if it were not for a strange U-turn as the aircraft size was originally dismissed by Airbus as having no business case.


The Airbus A220 family of aircraft was initially designed by Bombardier Aerospace as the

C- Series (CS100 and CS300), it was formally launched at the Farnborough Air Show in July 2008, the smaller of the two (CS100) performed its maiden flight on September 16", 2013, and entered commercial service on July 15th, 2016.

Goodrich Actuation Systems had been chosen for the design and production of a fully integrated high lift flap and slat actuation systems, and the thrust reverser actuation system.


During this period, Comar had worked with Goodrich Actuation Systems (now Collins Aerospace), providing qualification test rigs for the PDU, Flap & Slat Actuators, Thrust Reversers, Track Lock Valve, Outboard Brake, and the complete Half Wing test rig.

High Lift System Test Rig


A year later, in April 2017, Boeing filed a petition against Bombardier for selling the C-Series aircraft as a loss leader which posed a significant threat to the US aircraft industry, as a result of protracted court cases, the slow business and tough competition it forced Bombardier to enter a partnership with Airbus in October 2017 and the C-Series was rebranded as the Airbus A220.

All the development testing was not wasted, and Goodrich and Comar progressed to designing production test rigs, and as of February 2024, a total of 914 A220s had been ordered of which 322 had been delivered, disproving, Airbus’s original negativity to it being a viable aircraft.


The Power Drive Unit (PDU) is the motive force and control used for the Flap and Slat aircraft flying controls on the aircraft, it is a common part in both Slat and Flap Systems on this aircraft.

         Power Drive Unit

     Typical Flap & Slat System


Both PDU’s on the aircraft are controlled by the pilot via the aircraft Flap/Slat computer system, it is a hydraulically powered, electrically controlled unit which contains two fully independent drive channels with brakes and isolation valves, coupled with a speed summing differential, the PDU’s provide the transmission system with mechanical power through an output shaft as commanded by the pilot to drive the flap or slat surfaces against air loads.

Typical hydraulically driven Flap System


Having supplied Production test rigs for the Flap, Slat and Outboard Brake units, Comar’s brief for the PDU was to supply an Automated Test Equipment (ATE) rig to perform PAT Function Tests in accordance with detailed test configurations.


Standard procedure when developing a test rig is to follow Provisional Design Reviews (PDR) where concept designs and control systems are reviewed, Comar make use of Virtual Reality (VR) to demonstrate the ergonomics of the rig to the customer.

On acceptance, by the customer we proceed to Critical Design Review (CDR) where complete 3D CAD models are reviewed, system schematics, test procedures and safety integrity, finally the fully designed rig is demonstrated in VR.



   CDR Final Model for Review and Manufacture


To perform ATE testing, the Comar rig has a complex hydraulic system providing the motive power to the PDU hydraulic motors, each motor requiring, 28.5 lpm of Skydrol Fluid at 275 bar pressure from Moog RKP Radial piston pumps.


                            Hydraulics Assembly


                        Hydraulics CAD Model


The control system resides within a durable stainless steel industrial enclosure, ensuring reliability and longevity. A sleek aluminum-framed projective capacitive touch screen offers intuitive visualisation, complemented by a glass keyboard and touchpad for seamless operator interaction.

Every aspect of the tests undergoes meticulous monitoring and logging, including flow, pressure, temperature, torque, and speed. Additionally, performance characteristics specific to the aircraft unit are scrutinised, such as response times, gearbox backlash, motor leakage flow, and solenoid voltage and currents.

This project stands as a remarkable success for both Comar and our valued customer. We take great pride in our contribution to the C-Series / A220 journey.

If you have a requirement for test equipment at no matter what stage of level of comlexity we'd love to hear from you.

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