Helicopter Part Repairs

During my aerospace engineering co-op, one of my primary responsibilities was reverse engineering used aircraft components that require repair. Many aerospace parts, particularly for helicopters, were originally designed decades ago, and OEM drawings are often unavailable. This makes the reproduction of parts and the servicibility of helicopters very difficult. There were three components that I got to do reverse engineering work on while at XL Aero. Each of these parts is used on the Bell 214ST helicopter.

Seat Fitting

Subcomponent of an adapter assembly used for mounting passenger seats to the floor
Fitting is an aluminum part found on the end of passenger seat legs
Repair design included the remanufacturing of these fittings and replacing them within the adapter assemblies

Torsion Arm

Structural component that links the transmission to the fuselage
Alumimum arm (yellow) with elastomeric bushings (black) embedded inside
Elastomeric features are to allow for slight movement between fuselage and transmission
Repair design included re-moulding the elastomeric bushings and reusing the aluminum arm

Clevis Arm

Structural component that holds the torsion arm to the rest of the suspension system between the transmission and fuselage
Aluminum clevis (yellow) with elastomeric bushings (black) embedded inside
Repair design included re-moulding the elastomeric bushings and reusing the aluminum clevis

*** Note any manufacturing drawings or assembly diagrams cannot be shown for confidentiality purposes ***

Reverse Engineering

The reverse engineering of aircraft components is very detailed consisting of the following high-level procedure:

Critical dimensions identified

Ensures the production of a part with identical strength
Ensures the part will fit into any existing assemblies

Dimensional inspection performed using calibrated tooling
Apply tolerancing based on dimensional inspection

Tolerances must match any measured dimensions on the physical part

Material, temper, and surface treatment identification

Determined via XRF analysis and hardness testing for aluminum parts

Develop manufacturing drawing (GD&T applied)

Once the reverse engineering process was completed, coordination with suppliers was required to facilitate the manufacturing of QTY 200 fittings. The torsion and clevis arms were beginning the casting process of the rubber into the aluminum, but I never got to see the final result.

Final Product of Seat Fitting Repair
QTY 200 ordered by customer

Certification Process

Any repair designs (RDAs) that are made to aircrafts must be approved by Transport Canada. I helped with the certification process by preparing the following documents to be submitted for approval.

Compliance Plan

Used to outline the scope of work performed
Identifies which regulations the repair must conform to

Repair Instructions

Used by aircraft mechanics to actually perform the repair

Substantiation Report

Provides evidence that all regulations are met
Had to perform static load analysis to prove that fitting had sufficient strength

Takeaways

By performing reverse engineering on aircraft parts, I gained a massive appreciation for the amount of detailed work required to ensure safety during air travel. It was a great exercise to determine which dimensions are critical in terms of strength and fitment. By performing dimenisonal inspections myself, I learned a lot about different measurement tooling and the best ways to get accurate data. I learned best practices for applying tolerancing based on dimensional measurements. Coordintaing material analysis and manufacturing with suppliers was a great learning opportunity for how to get things made in the aerospace industry. Finally, I developed my technical writing skills conveying complex engineering information in a concise and clear manner for the delegates at Transport Canada to understand and approve.