Use this URL to cite or link to this record in EThOS:
Title: Development of a novel test rig for the evaluation of aircraft fuel tank sealants
Author: Hooper, Mark Nicholas
Awarding Body: Oxford Brookes University
Current Institution: Oxford Brookes University
Date of Award: 2007
Availability of Full Text:
Access from EThOS:
Leaks from aircraft fuel tanks have always represented a problem for aircraft manufacturers, airline operators and maintenance crews. The integral fuel tanks within aircraft structures are typically located within the wings and they rely upon sealant materials to prevent leakage past joints and fasteners. However, the wing is designed as a structural member first and as a fuel tank second and there exist many potential leak paths for the fuel from these complex, highly loaded structures. Fuel leaks result in direct loss offuel which may be dangerous, eause a loss in revenue due to aircraft being withdravvn from service and be difficult and expensive to repair. On top ofthis there arc important health and safety issues involved in the repair of fuel tanks, for example,the Royal Australian Air Force's, F-lll Deseal Reseal Programme 1979 to 2000, where it was found that a significant number of RAAF personnel involved in the Deseal Reseal Programme were suffering from a variety ofhealth problems. Current approaches to fuel tank sealant evaluation embrace immersion in a range of different fluids at different temperatures, ofboth bulk sealant samples and sealed joints. However, nearly all such tests are ofa 'static' nature and yet it is acknowledged that joint movement leads to leaks. Thus the missing component oftesting is movement coupled with the other key variables. The aircraft industry has been searching for a relatively simpllYtest method that can be used to evaluate sealed joint systems using realistic combinations of materials, joint geometries, imposed stresses and environmental conditions. The aim ofthis project was to do exactly this. A practieal but realistic dynamic test, the Model Sealed System (MSS), was designed, made and evaluated. This unique mechanism consists ofan axial stress machine into which fatigue, high and low temperatures and pressures can be programmed for automatic operation. A novel circular lap joint lies at the heart ofthe MSS in which test sealant is sandwiched between the circular coupons that are then assembled with aerospace fasteners and sealed. This joint configuration is representative ofa wing skin butt-strap joint in a real aircraft. The MSS is easy to run, it accurately simulates real world dynamics and conditioning, and it provides results to qualify sealants in a more realistic manner than current testing methods provide. The MSS enables evaluation and comparative testing of sealant systems when used for interfay, fillet and overcoat applications. The information provided is complementary to that obtained from conventional small scale coupon testing; it is not seen as a substitute. Further work is require~ to refine the test variables and further data arc required to provide confidence in the utility ofthe MSS. Development ofthe MSS was undertaken with the support ofAirbus UK to ensure that the design, materials and all other variables met \vith the overall requirements of a commercial aircraft manufacturer. Airbu·s UK have a duplicate MSS oftheir own, installed by the author, from which they can obtain patterns ofdata for different combinations of materials and experimental variables.
Supervisor: Not available Sponsor: Not available
Qualification Name: Oxford Brookes University, 2007 Qualification Level: Doctoral
EThOS ID:  DOI: Not available