Rigging the PW2000

Rigging the PW2000 By Greg Napert July 1999 Introduced in 1983 for the Boeing 757, the PW2000 is a two-spool, 37,000- to 43,000-pound engine, which has been also applied to military C-32 (757 military equivalent) and C-17 aircraft, as...

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Remember also, not to actuate the bellcrank with the rig pins installed, otherwise the pins will bend and/or linkage, brackets, and mounts will bend or break.

To review, the objective is to first rig the actuator to the bellcrank by pinning the bellcrank to a pre-set position and then adjusting the rod end of the actuator so that it connects to the bellcrank while it is in its full open position. Once that is accomplished, the variable vanes are rigged to the bellcrank by pinning the vanes in a pre-set position on the front split compressor cases and adjusting the linkages connecting the unison rings to the pinned bellcrank.

There are really two different procedures related to stator vane actuator rigging. In the case of replacing or installing components, or if you find that the engine is misrigged, you will be performing the stator vane actuator rigging from scratch. Otherwise, you will simply be performing a check of the rigging. The important point here is that different pins are required for checking the rigging versus actually performing the rigging and you've got to use the correct pins.

In either case, before you begin, you need to first verify that full movement of the stator vanes correlates with full movement of the actuator. To do this, you need to move the actuator through its full stroke while observing the stator vane unison rings (these are the ring like assemblies that connect all the stator vanes together around the circumference of the engine).

With this verified, you will next move the bellcrank down towards close and then up towards open until the rigging pin in the bellcrank can be inserted to hold the bellcrank in a Vane-Open position. This up and down stroke is important because it removes any play (hysteresis) from the linkage assemblies. Next, verify that the actuator is in the full open position by disconnecting it from the bellcrank and extending it to its internal mechanical stop position.

Jeche says, "This can also be done by two methods, manually by using specialty PWA pliers that force the hydraulic actuator into the full open position or by the hydraulic pump method. In fact, many technicians don't use the hydraulic cart while they are on the line because the pliers are much simpler."

When this is accomplished, you can rig the actuator to the bellcrank. Next, insert the rig pins on each stage of vanes through the "unison" rings and verify they line up with the rigging holes in the split case flange.

When you verify that all of the rigging pins are in and are in a fairly neutral position (not binding), you have confirmed the rigging.

Jeche adds, "If you have to tap, hammer, or otherwise force the pins into position, they are not properly adjusted. Also, if you have any damaged pins that are grooved or "chewed up," you should throw the pins away. You might be able to get damaged pins into the holes, but you won't be able to tell if you're in a neutral position. The rig "check" pins for the stator vane acuator allow for up to .005 inches error in either direction. These pins can be identified by a small step in the pin where they are machined to provide the .005 play in either direction. If you're rigging the stators, however, the "rig" pins are machined to precisely fit into the rigging holes. Use the appropriate pins for the operation you're performing and verify the part number of the pins.

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