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Automated Fluorescent Penetrant Inspection System (FPI) is Triple AT. L. Adair, Author
Pratt & Whitney - Support Equipment Operations
411 Silver Lane, M/S 129-50
USA, East Hartford, Connecticut 06108
D. H. Wehener, Co-Author
USAF - ASC/SMD
2145 Monahan Way, Bldg. 28, Room 300
USA, WPAFB, Ohio 45433-7010
Phone: (937)255-3330, ext. 3585
M. G. Kindrew, Technical Consultant
Pratt & Whitney - Military Engines
This paper describes how Fluorescent Penetrant Inspection (FPI) was used in the past, how it is used now and how it will be used in the future. The United States Air Force (USAF) and Pratt & Whitney (P&W) now use a fully-automated FPI process with manual visual inspection. With direction and funding provided by the USAF/Aeronautical System Center (ASC), these fully-automated FPI processors, located at Kelly Air Force Base in San Antonio, Texas were developed, manufactured, installed, qualified and put into operation by Pratt & Whitney. This paper will cover the following: the Qualification and Acceptance Tests (which include test objectives), test articles, test facility, test equipment, test results, and training.
This technology is affordable (lower processing cost resulting from increased throughput, reduced maintenance man-hours and reduced material consumption), adaptable (multiple industry applications, flexible layout accommodates simple, complex, large and small geometries), and accurate (improved reliability and detection capability through consistent processing). In addition, the FPI system is environmentally clean. P&W can design, manufacture, and install a customized FPI system for its customers. P&W is continually improving today's technologies and techniques to assure global readiness for the 21st century.
Automated Fluorescent Penetrant Inspection System
In the past, and in most situations even today, the USAF and P&W use an entirely manual FPI technique. Manual FPI is an eight step process consisting of surface preparation, penetrant application, pre-wash, emulsifier application, final rinse, drying developer application and inspection.
Manual FPI is a common method of non-destructive testing. However, it is hampered by liabilities such as inconsistent process flow, low throughput, susceptibility to material handling damage, and it is labor intensive.
The USAF's San Antonio Air Logistics Center (SA-ALC) now uses a fully-automated FPI process. This process is used to inspect most engine parts. Manual FPI is still used for some limited applications such as for areas that need special attention or for parts that the operator does not want penetrant to cover the entire part.
With direction and funding provided by the United States Air Force/Aeronautical Systems Center, these fully-automated FPI processors, located at Kelly Air Force Base in San Antonio, Texas, were designed, manufactured, installed and put into operation by P&W. Destination, qualification and acceptance testing were performed at San Antonio-Air Logistics Center.
Fully automated FPI is essentially the same process as manual FPI except the majority of the process is automated. Automation translates into quality improvements in process consistency, reliability, productivity, and environmental cleanliness. In a word, dependability. For instance, throughput has increased by over 100 percent, as compared to the manual FPI system. In addition, there are cost savings in materials and utilities versus the manual FPI system. Except for the manual placement and removal of parts from the processing line fixtures, the actual FPI preparation is fully-automated.
The test facility interface includes the following:
|Fresh water:||135 GPM at 35 psi ambient temperature|
|Compressed air:||300 SCFM at 85 psi|
|Drain:||80 GPM capacity|
|Steam:||2000 pounds per hour at 40psi|
|Electrical:||480 VAC, three-phase with 1,000 amps maximum current draw|
The following test equipment and materials were required for the qualification and testing of the processors and their associated adapter kits:
The best possible inspection for any product that requires inspection is affordable. FPI prevents premature failure, which is extremely costly. Even though the system is somewhat costly to install, the benefits include; reduced manpower, increased consistency, increased reliability, increased throughput and more accurate detection which results in fewer parts being parts with suspected defects. Return of investment can also be achieved through lower chemical consumption, water usage, disposal costs and better utilization of labor skills to operate the system.
There are three separate FPI processors in operation at Kelly AFB. The processors, all located in the same general area, were constructed using a modular concept installed with different sized station openings and layouts to enhance their adaptability to process a wide variety of part sizes. The processors are also adaptable to available floor space. The system includes a Large Parts Processor (LPP), a Small Parts Processor (SPP) and a Drum Rotor Processor (DRP). Each performs the same basic functions, except that each is optimized to process parts of a certain size and geometry.
A detailed diagram of arrangement of the Processor stations under the test conveyor loop and final configuration of the conveyor is provided in Figure 1.
|Fig 1: Typical Processor Adaptable Layout Under The Test Conveyor Loop.|
Test operators performed a Qualification and Acceptance test to provide step-by-step verification. It demonstrated that the LPP, SPP, and DRP and their associated Adapter Kits conform to functional requirements spelled out in the Configuration Item Development Specification (CIDS), and Software Product Specification (SPS). Also, the ability to operate the FPI processor computers from a software backup was demonstrated using the installation and reload instructions in the Software Users' Manual.
The successful completion of the Qualification and Acceptance Tests demonstrated that the LPP, SPP and DRP and their associated adapter kits are capable of reliably processing the family of F100-PW-229 engine parts. This is in accordance with the applicable sections of the Technical Order 33B-1-1, FPM Master and Supplement, MIL-STD-6866 and FPI Processor System Specification.
The automated FPI system is extremely accurate. The process achieved at least a 90 percent probability of crack detection (POD) at a 50 percent confidence level (CL) for a crack length of 0.040 inch, all tests. These automated FPI processors at SA-ALC are the first systems sold in the world based on POD.
The system uses 90 percent reclaimed water for the pre-rinse station. This equates to 14,616 gallons of water saved per year. Secondary containment is provided for the penetrate and emulsifier supply drums. The mist collectors for penetrant spray prevent vapor from escaping to the outside air or into the facility environment. Each station that uses facility water has a filter to remove the particulate contamination, a regulator to set the spray pressure and a backflow preventor or a three inch air gap to prevent any backflow into the facility water supply. Also, each station has a filter or regulator located in the incoming air line to regulate the air supply and to remove the moisture and particulate contamination. There are containment pans under all wet stations to contain spills. Computer control of process optimizes chemical usage to minimize generation of hazardous waste. The product can be processed and inspected without being touched by human hands, if necessary. All these features keep the work site safe, clean, and efficient.
Systems, automated or manual, require a degree of skill to operate, maintain records, and conduct systems checks that will keep the processor performing to its peak capacity, reliability and capability.
Pratt & Whitney can certify a system and provide training to familiarize operators and personnel with the maintenance requirements and characteristics of the automated FPI system, and related system software. The scope of training may include:
If there are a number of people requiring training in FPI, P&W can set up an American Society of Nondestructive Testing (ASNT) or International Standard Organization (ISO) approved schools so that the lowest level of training in FPI can be accomplished. To operate the system, an operator should be at least a Level I inspector. The operator must be able to spot trouble with the FPI process before it becomes a serious problem to the inspectors performing the inspection. P&W can also provide inspector certification testing to check inspector capability. Each inspector is tested and a POD is determined for his or her capability and probability to detect flaws. Training is still one of the most important points when the investment has the potential for the best automated FPI system in the world.
The technology is triple A - affordable, adaptable and accurate. Fully-automated FPI will provide lower processing cost with reduced inspection time, provide more precise results with improved reliability and detection capability, provide system layout flexibility to accommodate simple, complex, large and small part geometries, and improve environmental cleanliness. Just as today's weapon systems will give way to tomorrow's advancements, Pratt & Whitney is continually improving today's inspection technologies and techniques to secure global readiness for the 21st century.
P&W can: design, procure and install a customized automated FPI system; certify the system and personnel. With installation of an automated FPI system, the customers will enjoy several benefits.
NOTE: Automated FPI was one of the exhibits featured by Pratt & Whitney in it's award-winning "Best Medium Commercial Booth" at AUTOTESTCON '97 and AUTOTESTCON '00
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