Auxiliary power units (APUs) provide essential power while enduring extreme temperatures that cause significant wear and damage. Routine inspections are crucial in ensuring these small but mighty engines are in top shape. But when an APU fails inspection, it’s time to call Advanced Materials Technologies (AMT).
The APU Hot Section Repair Process at AMT
AMT is an FAA-certified Part 145 repair station specializing in commercial APU hot section turbine repairs. Our repair process focuses on restoring worn turbine components to meet applicable FAA requirements while maximizing the value of recoverable parts. We manage every step of the repair process from start to finish without relying on outsourced services, so you can expect fast, efficient turnaround times.
Step 1: Component Inspection
The first step in our repair process is evaluating the APU component’s condition to determine the extent of its damage and whether it can be repaired. Prolonged exposure to high temperatures can cause varying degrees of wear, erosion, and other damage. Some parts can be restored through conventional methods like welding or brazing, while others may be too severely damaged for traditional repair.
However, just because a standard repair might not be enough to restore a part doesn’t automatically mean it’s scrap. Our proprietary casting replacement process can save you the cost of replacing the entire component with a new OEM component. Casting replacement yields approximately 99.9%, compared to a typical book repair yield of 30-40%.
Most parts are more repairable than you think, but we understand how frustrating it is to send a part for repair only to find out it’s not an option. For borderline parts like bladed disc rotors, we can photo pre-screen over the phone to determine the part’s repairability before you even have to think about packaging and shipping.
Step 2: Advanced Cleaning and Surface Preparation
Before we begin the repair process, we thoroughly strip and clean the damaged APU hot section component. Removing accumulated deposits, oxidation, and other surface contaminants helps our technicians properly evaluate the part’s condition and prepare it for restoration. We clean APU components in-house for a quick and smooth transition from inspection to repair.
Step 3: Repair and Restoration
Repairing an APU hot section component depends on the type and level of wear. We’re experienced in standard processes such as welding and brazing to repair cracks, grinding and blasting to remove oxidation, and heat treatment to relieve internal thermal stresses. We also develop specialized repair solutions for complex and out-of-production components.
And for components that typically get scrapped, we use our proprietary APU casting replacement process. Instead of discarding the entire component, we preserve a sliver of the original part and braze it onto a new casting. If you deal with recurring hot section damage that leads to frequent, expensive replacements, casting replacement can save you both the money and the headache.
Step 4: Quality Control, Testing, and Final Verification
At AMT, we build quality assurance into every stage of the APU repair process. Our quality management system complies with ISO 9001:2015 and AS9100 standards. We use advanced inspection equipment, an in-house inspection team, and rigorous inspection procedures to ensure consistent, aerospace-grade precision.
Our in-house team comprehensively inspects and tests every repaired APU hot section component to verify it meets applicable requirements before returning to service. Our quality control process includes:
- Non-Destructive Testing: We use advanced NDT methods like Fluorescent Penetrant Inspection to detect cracks, surface defects, and other flaws without compromising structural integrity.
- Airflow Testing: We verify that applicable turbine components meet required airflow specifications and operating parameters.
- Dimensional Inspection: Our facility houses four coordinate measuring machines (CMMs), allowing us to perform precise dimensional and tolerancing measurements on complex geometries.
- Precision Hand Finishing: Our technicians carefully hand-finish repaired parts to meet exact dimensional requirements and surface finish specifications.
- Final Documentation and Traceability: Eligible components receive the applicable FAA Form 8130-3 Authorized Release Certificate, documenting their approved release status.
Looking for a Reliable Partner for APU Hot Section Repairs?
Contact Advanced Materials Technologies to discuss your APU component repair needs or arrange preliminary photo screening. Our team is ready to help you save time and money with reliable FAA-certified repair and restoration.
Images used under creative commons license – commercial use (10/26/2026). Photo by Bao Menglong on Unsplash