The L-733 provides the user with a portable reference system that incorporates a "waterline," "buttock line," and a "station plane" in a common instrument. Generally, 7 reference targets are required to set up and transfer the reference system inside the aircraft. The user places 3 targets into fixtures that represent the waterline of the aircraft, then places 2 targets onto fixtures that mount into the actual seat track. Next 2 targets are placed into fixtures that represent the "station plane," which is perpendicular to the seat tracks.
To start the setup, the horizontal laser plane is "bucked in" so that it is parallel to the 3 waterline reference targets. To accomplish this, the targets are all zeroed on the same reference point and placed into the waterline fixtures. The laser plane is then adjusted until all of the readouts display the same number, which means it is parallel to the waterline. The targets can then be taken back to the original zero reference and re-zeroed. This allows the operator to work from a zero number, rather than an offset number
The second part of the laser setup involves "bucking in" one of the vertical laser planes to 2 points along the "buttock line," using horizontally mounted targets. Using the azimuth adjustment on the L-123 PRY base, the laser is adjusted so that both reference targets display the same reading. Again, the targets can then be returned to the original zero point and re-zeroed.
Now, two measuring targets are mounted into a fixture, one horizontally and one vertically, that clamps into the seat track locations. At the point closest to the laser, both targets are zeroed out. One target measures from the vertical plane and one from the horizontal plane. The targets measure vertical and horizontal straightness simultaneously as they are moved down a seat track. If errors are found, dynamic adjustment of those points can also be accomplished from this set up.
To transfer the "buttock line," reference and measure any additional seat tracks for parallelism, the user must record the readings of the two targets mounted in the "station plane" (square to the "buttock line," locations. Next, the laser and base are moved to the next seat track location. The laser is then "bucked in" to the "waterline," targets. The azimuth is used to adjust the vertical laser plane such that the "station plane" targets read the same numbers that they did before the laser transfer. Now, the "buttock line"plane is exactly parallel to where it was at the previous seat track location. This process is repeated until all seat tracks are measured and aligned and parallel.