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The B747 lightweight assembly consists of an aluminium, CNC machined window plug, and an optional spacer ring. All parts have Parts Manufacture Approval (PMA) and are certified via a Supplement Type Certificate (STC) with worldwide validation. The assembly uses the same seal and retaining clips as the acrylic window assembly already on the airplane for ease and economy of installation. The spacer ring is used in lieu of the acrylic middle pane for additional weight savings and to reduce maintenance by eliminating all acrylic elements. The assembly has also been certified by FAA test to negate the requirement for a bonding strap to simplify installation still further. Detailed installation and maintenance instructions are provided for in service inspection and repair.
The part numbers used at each location are shown below.
Part Number & Location
- LAP 4003-1 Main deck STA 329.49 thru 2070.45
- LAP 4003-3 Main deck STA 269.45 thru 309.42 and STA 2090.45 thru 2270.45
- LAP 4003-7 Main deck STA 229.30 and 249.17
- LAP 4003-9 Main deck STA 148.50 thru 208.93
- LAP 4004-1 All Upper deck locations except STA 470.45 and 490.45
- LAP 4004-3 Upper deck STA 470.45 and 490.45
- LAP5003-1 Spacer Ring All window locations
Benefits of using lightweight window plugs:
Saves weight: The window plug weighs 1.2 pounds the spacer ring weighs 0.3 pounds. The weight of the acrylic windows being replaced is 4.2 pounds which results in a 2.7 pounds weight savings per window and 500 pounds per airplane for a typical passenger-to-freighter conversion (185 windows) and considerably more if replacing the Original Equipment Manufacturer (OEM) window plug installation.
Saves fuel: At today’s fuel prices the window plug installation can pay for itself in just over two years.
Saves money: Lower component cost.
Easy to use: Simple as replacing a window.
Less installation time: The assembly has been certified by FAA test to negate the requirement for a bonding strap which considerably reduces installation time.
Lower maintenance: All acrylic elements require frequent inspection. The use of the spacer ring eliminates all acrylic elements therefore significantly reducing maintenance.
Proven reliability: All parts are PMA approved and certified via FAA STC and worldwide validation. To date there are more than 40,000 parts in service with a perfect history.