BGA AIRWORTHINESS AND MAINTENANCE PROCEDURES PART 4, LEAFLET 4-8
MAINTENANCE OF SEAT HARNESSESS AND BELTS

GENERAL
1. Various types of seat harnesses are fitted to gliders ranging from simple 4 point harnesses to aerobatic 5 point harnesses. Each harness must be capable of restraining the occupant in his/her initial position during all phases of flight and in emergency situations and releasing when required and not prematurely.
CLEANING
2. Seat harnesses should only be cleaned using soap or mild household detergent and warm water and rinsed in clean water, then allowed to dry. Never use excessive heat to speed up drying and avoid getting any Quick Release unit wet. Solvents and harsh detergents must not be used.
LUBRICATION
3. Quick release units may require some lubrication from time to time. This should be done sparingly and only light oil should be used. If available, always follow the manufacturers recommendations. Too much lubricant will attract dirt and fluff also will leak onto clothes.
INSPECTION
9. (a) Webbing: The webbing should be checked for abrasions, wear, damage, pulled or loose stitching. Some very minor abrasion is acceptable where the belt is regularly adjusted. Pay particular attention to the edges of the straps where they pass through slots or guides. Any edge wear, cuts or abrasions in these areas are cause for rejection. (b) Buckles: Buckles should be checked for wear, especially on the knurled locking bar, cracks and corrosion. Plastic buckles should be replaced with metal buckles. Adjustment buckles must be checked to ensure that they do not slip under load. (c) Attachments: The harness should be checked at each attachment point to ensure that the webbing is correctly fitted and doubled back through the attachment buckle. The aircraft attachment points should be checked for damage, security and condition. The aircraft structure should be inspected in the vicinity of the harness attachment points. (d) Quick release (QR) units: QR units should be checked for correct operation, positive locking when a seat harness is inserted, and smoothness of operation, ability of springs to return the control knob to the closed position. QR units should be checked for loose items internally by shaking or examination through fitting slots. If loose items are suspected the QR unit must be removed for inspection. A function test must be carried out with a person actually sitting in the seat to ensure the QR unit functions correctly in fastening and unfastening modes. QR units are not “in the Field” reparable as spare parts are not normally available and specialist test equipment is required to test after repair. If a “Transit” type unit is fitted and the upper restraint release is operational and not fastened locked, the operational lever must be checked for operation. It must not release on a hair trigger

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BGA AMP Part 4, Leaflet 4-8, page 1

but be positive in operation. Additionally the “Transit” release must not release the lap straps on disengagement or when the upper straps are refitted. (e) Metal QR fittings: The metal fittings that engage with the QR unit should be checked for condition paying special attention to wear, distortion and corrosion. (f) Proof testing: It is not recommended to carry out proof testing of harnesses unless you have the specialist equipment and information available. The harness could be permanently damaged and rendered unsafe by inappropriate proof testing. In a case of doubt about the serviceability of the harness, it should be replaced or entrusted to a specialist company for repair and testing.
HARNESSES RECOVERED FROM ACCIDENTS
5. It is not permitted to re-use any seat harness that has been recovered from an accident as it may well have been taken over the rated proof strength. The seat harness is a fundamental piece of safety equipment and it must be treated as such. All seat belts recovered from an accident should be destroyed unless it can be established without doubt, that the harness is serviceable. If the aircraft is being rebuilt, it is strongly recommended that new harnesses be fitted.
6. Only the manufacturers of the seat harness or approved repair facilities may re-certify seat harnesses recovered or salvaged after involvement in an accident. Full details of the accident must be supplied to the tester to enable an accurate assessment to be made.
7. Harnesses or seat belts fitted in aircraft involved in an accident may remain in service provided the certifying engineer is completely satisfied that the harness or seat belt was not subject to any abnormal loads.
MIX AND MATCH
8. The unauthorised mixing of different harness components is not permitted as even with the same manufacturers items, there could be a specification change and this may not be readily visible to the installer.
9. It is recommended that complete harness assemblies be changed as a unit unless the manufacturer supplies a specific item compatible with the existing assembly.
10. Old or unserviceable harnesses should be destroyed to prevent inappropriate use.

AMP 4-8/ 05/05

BGA AMP Part 4, Leaflet 4-8, page 2