NON-DESTRUCTIVE TESTING
The use of NDT inspection has grown over the years in both application and innovation and has done more to improve aircraft safety than almost any other existing technology.
Non-destructive inspection implies a method which will detect defects in parts or assemblies, while avoiding any damage to serviceable items. This is an integral part of the inspection process. At Progressive Air Group of Companies, our inspections are performed by a NDT technician fully qualified and licensed by NRCan.
Magnetic Particle Testing
Magnetic particle testing is used extensively to test such fracture critical items as crankshafts, connecting rods, mounts “hot section” components of an engine, for surface and sub-surface discontinuities.
Magnetic particle testing is ideally suited for the examination of ferromagnetic materials (iron, nickel, and cobalt alloys), but not for non-ferromagnetic materials (alloys of aluminum, magnesium, copper, titanium, and austenitic stainless steels).
During magnetic particle testing the part under test is magnetized with low voltage/high amperage equipment to a specified value. A mixture of base oil and fluorescent iron oxide particles is then applied over the entire surface of the test part.
If a flaw is present, such as a stress-related fracture, a magnetic leakage field forms around the defect. The fluorescent iron oxide particles migrate to the defect. They congregate at the site where the break in the alloys crystalline structure occurs. Visual examination by black light readily detects the indication.
Magnetic particle testing is economical and time saving. Magnetic particle inspection is a viable, cost-efficient method which is fundamental to the Aircraft maintenance inspection process.
SPECIFICATION STANDARDS
Magnetic Particle Testing
ASTM-E-1444
MIL STD-1907
LYCOMING OVERHAUL MANUAL
CONTINENTAL OVERHAUL MANUAL
SPECIAL PROCEDURES WRITTEN BY A LEVEL III NDT TECHNICIAN
Fluorescent Penetrant Testing
This is a non-destructive testing method best suited for finding discontinuities open to the surface in solid materials that are essentially non-porous.
Penetrants are low viscosity liquids specifically engineered to seep into the tightest flaws and hairline fractures due to capillary action. The penetrant contains a fluorescent compound that illuminates when exposed to ultraviolet light.
To conduct a fluorescent penetrant inspection (FPI), the item to be inspected must be clean and free from paints, dirt, and oil as these inhibit the penetrant's ability to enter open flaws.
Penetrant is then applied and allowed to "dwell" for a specified time established in the applicable procedure. After the penetrant is removed, a developer is applied to visually enhance any indications that may appear.
Penetrant inspection ranks as one of the most cost-effective test methods.
SPECIFICATION STANDARDS
Liquid Penetrant Inspection
ASTM-E-1417
MIL STD-1907
LYCOMING OVERHAUL MANUAL
CONTINENTAL OVERHAUL MANUAL
SPECIAL PROCEDURES WRITTEN BY A LEVEL III NDT TECHNICIAN
Ultrasonic Crankshaft inspection per Teledyne Continental
Motors SB
Ultrasonic testing introduces high frequency sound waves into the test material to detect sub-surface discontinuities. Transducers are used to both transmit and receive sound energy in the test article.
Test frequencies between 1 and 25 MHz are normally used. Cracks, laminations, shrinkage cavities, forging bursts, porosity, bonding faults, and other discontinuities with established metal-gas interfaces can easily be detected.
Common aircraft applications include,: thickness testing of aircraft skin and airframe structural members, crack detection, and corrosion evaluation.
Some advantages of the ultrasonic testing method include high penetrating capability, high sensitivity and resolution, portability, single surface accessibility, and the immediate interpretation of test results.
SPECIFICATION STANDARDS
Ultrasonic Inspection
CONTINENTAL SB MSB96-10B
SPECIAL PROCEDURES WRITTEN BY A LEVEL III NDT TECHNICIAN