The Plus of CBM+ Thomas H. Carroll III. Director of Aircraft Maintenance Technical Services

Transcription

1 The Plus of CBM+ Thomas H. Carroll III Director of Aircraft Maintenance Technical Services

2 The CBM+ Initiative has Immediate Benefits Reduction of scheduled preventive maintenance content Escalation of preventive maintenance intervals Early warning of impending failures through data link Enable scheduling of unscheduled maintenance Enhanced diagnostics for troubleshooting Optimized logistics support Pre-staging replacement parts for impending failures Less components replaced for preventive maintenance over the life of the equipment

3 These Benefits are Limited Operational Readiness is increased slightly because of less time spent in preventive maintenance Compared to the impact of unscheduled maintenance, preventive maintenance is a small piece of the pie Few failures in the field are actually moved to the scheduled environment Only systems / components with measurable degradation are good candidates for predictive failure monitoring The equipment is still out of service for repair Enhanced diagnostics will make the maintainers experts in repairing systems But the systems still break with the same regularity Where is the plus of CBM+?

4 It s In the + One of the + initiatives of CBM+ is Serialized Item Management (SIM) Repairable end items and sub-assemblies that are uniquely tracked, controlled or managed in maintenance, repair and / or supply by means of its serial number This tracking needs to include the recording of data from scheduled and unscheduled maintenance events of the end item and shop repair actions of the removed components / sub-assemblies The data must be collected in a centralized database and easily retrievable If these criteria are met, then quantum leaps in reliability and Operational Readiness can be achieved as the following examples illustrate

5 Problem 1: Nose Gear Bump Problem During cruise flight, the nose gear would bump in the wheel well This occurred sporadically across the fleet Impact Flight diversions Repeat complaints Extensive maintenance down time Analysis Detailed review of the aircraft maintenance data since delivery and nose gear strut shop history Problem started about 1.5 to 2 years after strut was modified with a new end cap End cap was noted to have backed off, which affected the uplock system and caused the nose gear to automatically re-retract Corrective Action OEM changed thread sealant spec for the nose gear strut end cap

6 May Jul Result 1: 77% Reduction of Complaints Nose Gear "Bump" in Flight Average = 4.8 Began corrective action May 2006 Average = 1.1 May Jul Sep Nov Jan 06 Mar May Jul Sep Nov Jan 07 Mar May Jul Sep Nov Jan 08 Mar Mar Jan 05 Number of Complaints

7 Problem 2: Slats Binding Problem During aircraft takeoff, the slats would bind during retraction This occurred when the aircraft was fully loaded and high angle of ascent The airframe OEM stated that this was a global fleet issue Impact Flight diversions Repeat complaints Extensive maintenance down time Analysis Detailed review of the aircraft maintenance data since delivery In a fleet of 24 aircraft, only 3 had exhibited the problem (not the oldest aircraft) The problems start after 1200 flight hours and got progressively more frequent Corrective Action OEM Engineering assessment of the 3 aircraft, reworking their slat mechanical systems

8 Result 2: Slats Binding Improvement Aircraft 1 Number of complaints prior to rework (3175 flight hours) = 10 Number of complaints after rework = (1612 flight hours) = 1 Aircraft 2 Number of complaints prior to rework (3418 flight hours) = 10 Number of complaints after rework = (1178 flight hours) = 1 Aircraft 3 Number of complaints prior to rework (1360 flight hours) = 5 Number of complaints after rework (1762 flight hours) = 0 OEM applied lessons learned to global fleet

9 Problem 3: APU Overspeed Light Problem High number of Auxiliary Power Unit (APU) overspeed light illuminates on shutdown complaints, indicating fault with APU system Numerous variations of a controller (3-speed switch) have been ineffective in improving system reliability Impact High number of flight delays and restricted operations Repeat complaints Extensive maintenance down time Analysis Detailed review of the aircraft maintenance data since delivery Revealed chronic aircraft caused by installing specific serial number 3-speed switches (Rogue Units) that exhibited repeated infant mortality Though they have failed, Rogue Units always bench check good Corrective Action OEM Engineering assessed the Rogue Units, modified the bench test procedure to identify and resolve the aberrant failure modes

10 60 50 Result : 77% Decrease in Complaints APU "Overspeed Light on Shutdown" Complaints Average = Began 3-Speed Switch Campaign Jan-95 Feb-95 Mar-95 Apr-95 May-95 Jun-95 Jul-95 Aug-95 Sep-95 Oct-95 Nov-95 Number of Complaints Completed 3-Speed Switch Campaign Average = 7.25

11 Problem 4: Autopilot Flight Control Computer Problem Poor autopilot system reliability Impact High number of repeat complaints High replacement activity of autopilot flight control computer (FCC) Extensive maintenance down time Poor logistics support Analysis Detailed review of the aircraft maintenance data since delivery Revealed chronic aircraft caused by installing specific serial number FCCs (Rogue Units) that exhibited repeated infant mortality Though they have failed, Rogue Units always bench check good Corrective Action OEM Engineering assessed the Rogue Units, modified the bench test procedure to identify and resolve the aberrant failure modes

12 Flight Control Computer 12 Month Rolling MTBUR (hours Jun'93 Sep'93 Dec'93 Mar'94 Jun'94 Sep'94 Dec'94 Mar'95 Jun'95 Sep'95 Dec'95 Ma '96 Jun'96 Sep'96 Dec'96 Mar'97 Jun'97 Sep'97 Dec'97 Mar'98 Jun'98 Sep'98 Dec'98 Result 4: 77% Increase in MTBUR Repaired Rogue Units Average 6294 hours Average 3554 hours

13 Problem 5: Radio Altimeter Transceiver Problem Poor radio altimeter system reliability Impact Repeat complaints High replacement activity of transceiver Extensive maintenance down time Poor logistics support Analysis Detailed review of the aircraft maintenance data since delivery Revealed chronic aircraft caused by installing specific serial number transceivers (Rogue Units) that exhibited repeated infant mortality Though they have failed, Rogue Units always bench check good Corrective Action OEM Engineering assessed the Rogue Units, modified the bench test procedure to identify and resolve the aberrant failure modes

14 Radio Altimeter Transceiver 6 Month Rolling MTBUR (hours) Sep-95 Dec-95 Mar-96 Jun-96 Sep-96 Dec-96 Mar-97 Jun-97 Sep-97 Dec-97 Mar-98 Jun-98 Sep-98 Dec-98 Mar-99 Jun-99 Sep-99 Dec-99 Result 5: 98% Increase in MTBUR Repaired Rogue Units Average 23,815 hours Average 12,007 hours

15 Problem 6: Flight Augmentation Computer Problem Poor autopilot flight augmentation system reliability Impact High number of repeat complaints High replacement activity of flight augmentation computer (FAC) Extensive maintenance down time Poor logistics support Analysis Detailed review of the aircraft maintenance data since delivery Revealed chronic aircraft caused by installing specific serial number FACs (Rogue Units) that exhibited repeated infant mortality Though they have failed, Rogue Units always bench check good Corrective Action OEM Engineering assessed the Rogue Units, modified the bench test procedure to identify and resolve the aberrant failure modes

16 Result 6: Results = 141% Increase in MTBUR Flight Augmentation Computer Repaired Rogue Units Average 3564 hours Average 1479 hours Month Rolling MTBUR (hours) Jul'93 Oct'93 Jan '94 Apr '94 Jul '94 Oct '94 Jan '95 Apr '95 Jul '95 Oct '95 Jan '96 Apr '96 Jul '96 Oct '96 Jan '97 Apr '97 Jul '97 Oct '97 Jan'98 Apr'98 Jul'98 Oct'98

17 Problem 7: Autopilot Mode Control Panel Problem Poor autopilot system reliability Impact Repeat complaints High replacement activity of autopilot mode control panel (MCP) Extensive maintenance down time Poor logistics support Analysis Detailed review of the aircraft maintenance data since delivery Revealed chronic aircraft caused by installing specific serial number MCPs (Rogue Units) that exhibited repeated infant mortality Though they have failed, Rogue Units always bench check good Corrective Action OEM Engineering assessed the Rogue Units, modified the bench test procedure to identify and resolve the aberrant failure modes

18 25000 Result 7: 148% Improvement in MTBUR Autopilot Mode Control Panel Average 15,015 Hours MTBUR (hours) Average 6,066 Hours Repaired Rogue Units

19 Analysis Technique Examples Perform surveillance of individual end items for repetitive system complaints Determine final repair actions lessons learned Assess end item group maintenance data Common system / hardware problems Maintenance program shortcomings Age-related issues Review individual component performance Rogue Units Life limits Batch problems OEM part number differences Shop repair problems Depth of repair when sent to shop (overhaul vs. repair)

20 SIM Data Requirements Assign end item a specific tracking number Mainframe data collection program Group common end item maintenance events Create unique end item system identifiers I.E.: Electrical power generation = 24 Collect end item maintenance history Enter all maintenance complaints and corrective actions in appropriate end item system data sets End item serial number Date of complaint, corrective action Narrative of complaint, corrective action Enter component replacements Part Number Serial Number (if applicable) Installation position in end item (left, right, 1, 2, etc.) Reason for removal (scheduled, unscheduled, other )

21 Benefits of Focusing on the + Quick quantum leaps in end item system reliability and Operational Readiness Identification and resolution of failure root causes, not just mitigation of failures Reduction of unscheduled maintenance Improvement of scheduled preventive maintenance, predicated on real-life field data Improved logistics effectiveness and reduction of spare inventory

22 Questions?