Aviation safety issues and actions

Difference between drawing datum and coordinate measuring machine datum

Issue number: AO-2010-089-SI-07
Who it affects: Engine manufacturer Rolls-Royce plc
Issue owner: Rolls-Royce
Transport function: Aviation: Air transport
Background: Investigation Report AO-2010-089
Issue release date: 27 June 2013
Current issue status: Adequately addressed

Safety issue description

The coordinate measuring machine was programmed to measure the location of the oil feed stub pipe interference bore with respect to the manufacturing datum, instead of the design definition datum as specified on both the design and manufacturing stage drawings.

Proactive Action

Action number: AO-2010-089-NSA-050
Action organisation: Rolls-Royce
Date: 27 June 2013
Action status: Closed

Rolls-Royce advised the ATSB that in July 2008, the design definition and manufacturing stage drawings had been changed to use the inner diameter of oil feed stub pipe as the datum for the oil feed stub pipe counter bore. During March and April 2009 both the manufacturing process and the coordinate measuring machine program were changed to use that revised datum. Use of the original manufacturing datum was discontinued.

ATSB comment:

The ATSB is satisfied that the action taken by Rolls-Royce adequately addresses this safety issue and therefore makes no recommendation.

Last update 08 January 2014