U.S.Patent 115218.00001
All Rights Reserved

R.A.B. Radial, Axial, Bearing Measuring Tool Kit

PART NUMBER:                  RABK6977                                                                          NSN:  5180-01-572-1858

AIRCRAFT APPLICATION:              AH-64                    OH-58                   UH-1                      CH-47

SYSTEM USED ON: Main Rotor/Tail Rotor pitch control rods, flight control rods, servos, and linkages requiring bearing measurement INSPECTION AND replacement

MAINTENANCE LEVEL:                   AVUM                  AVIM                    DEPOT


The R.A.B. (Radial Axial Bearing) Tool Kit is designed to measure the RADIAL and AXIAL allowable variation and tolerance of the AH-64 Apache Helicopter Main Rotor (M/R) and Tail Rotor (T/R) Pitch Change Link Spherical Bearings, to include any other helicopter platform using metallic spherical bearings requiring accurate axial and radial measurement. The R.A.B. also includes a “Trammel” Tool designed to perform center to center rod-end bearing measurements to within 0.01″ for AH-64 series (M/R) Pitch Change Link Spherical Bearings requiring specific bearing measurement replacement, as specified in the IETM and Maintenance Manuals for trammeling tasks. It can also be expanded to accommodate other helicopter platforms requiring similar maintenance procedures.

The RAB Tool Set is self-contained in its own militarized packaging MIL-SPEC container to ensure storage, preservation, and accountability. Each component has a shadow box location in the container for ease of inspection and identification. It includes a demonstrational and instructional DVD, and a laminated operation instruction card.


During use, the RAB provides accurate radial and axial bearing measurement when on-aircraft bearing inspection and play measuring not reliable or accurate and when bearing measurement is required, per IETM. This includes the M/R trammeling tasks when bearing replacement is required. The RAB also replaces current measurement and rigging shop-aids and standardizes maintenance procedures. Nominal settings lead to additional run-up’s during rotor smoothing Maintenance Test Flights.

 WEIGHTS/DIMENSIONS:              WT: 30.0 lbs.      Size:  RAB:  20.0”L x 14.0”W x 12.0”D / Container: 24.0”L x 18.0”W x 18.0”D

TM/IETM TASK REFERENCE(S): Dept. of the Army Interactive Electronic Technical Manual (IETM); Longbow Apache TM 1-1520-LONGBOW/APACHE, IETM V12.1. Army Aviation & Missile Research Development & Engineering Center (AMRDEC).