Problem:

Talon Aerospace developed a product that replaces the incandescent aft navigation lights with LED’s for the Boeing 737. Because the power supply failed often, Talon’s profits on this product were being eroded by warranty work. The power supply needed to be re-designed, and the projected timeline was over one year.

Analysis:

After reviewing the current power supply design, the design requirements, and the DO-160 Environmental Conditions and Test Procedures, I estimated that the power supply could be redesigned with a prototype ready for FAA testing in three months.

I also investigated what was causing the power supplies to fail. Although the current design had its faults, it was determined that power surges from the aircraft exceeding Boeing’s specifications was also killing the LED power supplies.

Solution:

The basic steps for getting this turned around in a short time included:

• Creating a specifications document for the power supply. Specifying exactly what needs to be designed is critical to a successful design.
• Outsourcing the power supply design. Talon’s in-house design team was backlogged with work, and there are design firms that specialize in designing power supplies.
• Frequent design reviews. The risk for scope creep was high with this project, and a frequent review of scope and specifications versus design kept everyone focused on getting this done on time.
• Warranty voider circuity. If the power supply experienced a power surge exceeding the specifications of Boeing, an electronic component would leave a permanent mark on the circuit board expressing that the warranty was voided.

Results:

I found a freelance electrical engineer who specialized in designing electrical control circuits for military aircraft. We reviewed the preliminary design requirements document and created the design specifications document. With weekly design reviews and SPICE modeling, a design for prototype was completed. In the three-month estimated time frame, three prototype circuits were made for FAA testing.

The prototypes were tested in an FAA certified facility and the prototypes passed for the environmental test conditions. Talon was then able to put the design into production, and the new power supplies on the Boeing 737.