01 Jan Aircraft Lap Joint Modifications Keep an Aircraft Flying
Aircraft lap joint modifications
Specialist teams embody lap joint modifications and aircraft structural repairs on fleets of 737-200’s and and 737-200 cargo aircraft and also 737-300 with increasing frequency.
Determined by the Lap Joint SB 1177, only Licensed EASA AND FAA structures engineers can oversee this type of project. SB737-53-1179 and SB737-53A-1210 have also been applied to these aircraft.
Unforeseen defects can be found on inspection during this modification. Aircraft structural repairs for this same reason can also be required outside the scope of SB737-53A-1177.
Airwothiness directives for all Boeing 737-100, -200, -200C, -300, -400, and -500 series aircraft, have become prevalant for the unsafe condition of fuselage skin cracks adjacent to the skin lap joints due to scribe lines. This damage can be a hidden problem, often hidden under resealed or repainted surfaces. Cracks develop after the aircraft has returned to service, can initiate at any point, or at multiple points, along the length of the scribe line. Established cracks in the wing structure can link up. The damage is caused by using the wrong tools for removing paint or decals.
Scribe line damage can also occur at many other locations, including butt joints, external doublers, door scuff plates, the wing-to-body fairing, and areas of the fuselage where decals have been applied or removed. Rapid decompression of the aircraft can be the result of fatigue cracks resulting from scribe lines on the pressurized fuselage structure.
The remedy consists initially of inspection for cracks in the fuselage skin at lap joints, butt joints and external repair doublers. Detailed inspection is defined as an intensive visual examination to detect damage, failure, or irregularity. Intense lighting, surface cleaning and elaborate access procedures may be required.