The Sunaero military system and 28 Vdc thermoreactor.
Fuel leaks have plagued the aircraft industry for decades. When a jet develops a fuel leak, the result can be three to five days of costly ground time due to standard troubleshooting and repair methods that entail three time-consuming issues: finding the leak source within the tank, sealant curing (polymerization), and the likely potential for releaks. Traditionally, final quality control of the repair is performed when the aircraft is refueled. In the event of a releak, the whole repair process is brought back to square one. "Leak location and polymerization have always been major trouble for operators and manufacturers alike," said Alain Marechal from Airbus Industrie, Toulouse, France.
To help solve the dilemma, European aircraft manufacturers, airlines, and maintenance centers have turned to the helium leak detector from the French company Helitech and thermoreactor curing technology developed by Sunaero SA - Fig. 1. Both technologies are presently in use at all French Air Force sites and French naval aviation facilities, including on board the aircraft carrier Charles de Gaulle.
Fig. 1 - The Sunaero airline system and rapid curing using the 28 Vdc thermoreactor.
Helium Leak Detection
The helium leak detector system uses a sensor technology technique 1000 times more sensitive than any other existing technology - Fig. 2. It has a 95% success rate for locating fuel leak sources (compared to 60% using the bubble method). Helium is pumped into the fuel tank at the leak location. A probe is then passed slowly above the test area, inside the tank, and a signal is given when the leak source is located. This allows for specific pinpointing of the leak source. Once the leak repair has been accomplished, the helium leak detector confirms the repair has been made before the tank is refueled. Quality control is made possible by "dry mapping" the fuel tanks with helium prior to refueling. If another tank entry is required, it can be accomplished almost immediately. The many hours of preparation to reenter a "wet" tank are, as a result, unnecessary.
Thermoreactor Curing Technology
Thermoreactor curing technology uses a specific infrared, catalytic panel to cure sealant. Test results by Airbus on a PR-1422 B2 sealant (Le joint Francais) have proven that under theoretical curing conditions (77°F and 50% relative humidity), 35 "A" shore hardness was reached after 30 h and final hardness after 72 h. Thermoreactor curing technology, however, reduces curing time to only 2.75 h; a fully cured sealant is done in only 6 h. Developed to be completely safe when used inside the fuel tank, this technology is an efficient way to cure/polymerize tank sealant.
Fig. 2 - The Helitest Wing helium leak detection system.
More Flight Hours For Operators
Because it can ensure a high probability of leak source pinpointing, the helium leak detector will save several days of an airplane being out of service even if repair work is performed in a difficult area within the fuel tank. It is estimated the final helium mapping of the tanks, standing as a quality control tool, will allow a savings of more than one day in the event of an unsuccessful initial repair (i.e., releak). Downtime would also be greatly reduced when using the thermoreactor curing technology; the published cure time of the sealant, for example, has been found to be one-twelfth what it would otherwise be, and could be even more so in cold weather conditions. Furthermore, thermoreactor curing technology can be used on aircraft paint jobs, dividing by thirty to fifty the polymerization time of the paint. Both Boeing and Airbus endorse the helium leak detector and thermoreactor curing technology. Dedicated procedures have since been introduced into most aircraft maintenance manuals.
Bringing the Technology to the Americas
To support aircraft operators on a worldwide scale, Aerowing was formed in the United States and based in Miami, Fla., to introduce this maintenance technology to North and South America. The company's products are aimed at helping to increase aircraft utilization and reduce downtime and scheduled maintenance flowtime by providing advanced testing and repair solutions on airframe structure, fuel and fluid systems, composites, and painted surfaces. The company plans to provide European technologies, according to U.S. standards, as well as introduce new U.S. products that will benefit the aviation industry. Training sessions will be given at the company training center.
Information provided by the French Technology Press Office, (312) 222-1235, Chicago, Ill.
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U.S. Benefits from European Leak Detection Technology