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					               TOMELLERI                                                    Nonconformance Report

Date: 03/01/08                Originator: R. Tomelleri                                          Page 1 of 1
                                                                                                Attachment: 1
NCR-°: NCR-VST-TOM-001                    Revision n. 0                                               Critical Item:          Yes
NCR Title:      Axial Actuator Force Decay
VIOLETED REQUIREMENT: R 46 - VST-SPE-OAC-22000-1311 Issue 1.4
SUPPLIER:                                      PROCEDURE n.:
ITEM NAME:                                     PART Number :
UNIT NAME:      Axial Actuator                 Serial PART n. :
SUBSYSTEM:      M1 Axial Support System        Purchase order n.:

NC stated during:             □ Incoming                           □ Manufacturing                      □ Assembly
                              □ Integration                        ■ Test                               □ Acceptance Test
                              □ Inspection                         □ Other:
Description of Non-Conformance:
During some internal tests, the accuracy of the actuator has been verified with the reaction bracket applied to the
actuator. The load reaches the controlled value with the correct accuracy until the load is under control.

On the other hand, after the motor has been disabled, the load changes of a certain amount in some minutes ( from 0.5
N until 6 N ), depending on the amplitude of the last step and depending on the sign. In the previous version of the
actuator provided by INAF, the load change was 0.8 N. The cause of the load change is probably due to the
accommodation of disk springs inside the housing caused by the friction among the springs and the housing surface.

 Nonconformity Classification:

 ■ Major            □ Minor                □ Observation
Cause of NC:                  ■ HW Design                          □ Manufacturing                      □ Process
                              □ SW Design                          □ Part defect                        □ Testing
                              □ Documentation                      □ Other                              □ Trans./handl.

Disposition and Corrective/Preventive Actions:                                            Disposition Performed:
Change the springs using six coil springs instead of the disk springs (see
annexed drawing). This solution avoids any contact among the springs and other Procurement of new coil springs.
surfaces. Further, the solution uses a ball bush for the guidance of the pusher in
order to avoid any other friction. Another advantage of this solution is the linear
behavior of the coil spring.
                                RESERVED FOR USE BY VST TEAM SECRETARIAT
Date of registration:       Order of Priority for Appr. / Impl.: 1 (high)     ■      2 (medium)                   3 (low) 

                            Qualification Status:                  Qualified        In process of qualification       ■
NCR Closure                  ■ YES                   
     INTERNAL           X       Project Engineer X    Project Manager    X    Principal Investigator     X   S/S Responsible
   DISTRIBUTION                 P. Schipani           G. De Paris             M. Capaccioli                  D. Fierro

                                   RESERVED FOR USE BY VST Project Engineer
Approved                            Date and signature (VST PE)
■Yes No

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