Aircraft Maintenance Data: Does it Matter?

Transcription

1 Warner Robins Air Logistics Center Engineering Aircraft Maintenance Data: Does it Matter? Panel Session: Reliability Based Approaches for Design and Sustainment Russ Alford WR-ALC/ENFA

2 Background Following this chart is NMC data for 18 different MDS The first chart for each a/c shows Total Not Mission Capable Supply (TNMCS) and Total Not Mission Capable Maintenance (TNMCM) TNMCS is the gold area TNMCM is the gray area The second chart for each a/c shows Not Mission Capable Maintenance Scheduled (NMCMS) and Not Mission Capable Maintenance Unscheduled (NMCMU) NMCMS is the blue area NMCMU is the red area Data from the Air Force Common Operating Picture

3 Aircraft 1 TNMCM TNMCS

4 Aircraft 1 NMCMU NMCMS

5 Aircraft 2 TNMCM TNMCS

6 Aircraft 2 NMCMU NMCMS

7 Aircraft 3 TNMCM TNMCS

8 Aircraft 3 NMCMU NMCMS

9 Aircraft 4 TNMCM TNMCS

10 Aircraft 4 NMCMU NMCMS

11 Aircraft 5 TNMCM TNMCS

12 Aircraft 5 NMCMU NMCMS

13 Aircraft 6 TNMCM TNMCS

14 Aircraft 6 NMCMU NMCMS

15 Aircraft 7 TNMCM TNMCS

16 Aircraft 7 NMCMU NMCMS

17 Aircraft 8 TNMCM TNMCS

18 Aircraft 8 NMCMU NMCMS

19 Aircraft 9 TNMCM TNMCS

20 Aircraft 9 NMCMU NMCMS

21 Aircraft 10 TNMCM TNMCS

22 Aircraft 10 NMCMU NMCMS

23 Aircraft 11 TNMCM TNMCS

24 Aircraft 11 NMCMU NMCMS

25 Aircraft 12 TNMCM TNMCS

26 Aircraft 12 NMCMU NMCMS

27 Aircraft 13 TNMCM TNMCS

28 Aircraft 13 NMCMU NMCMS

29 Aircraft 14 TNMCM TNMCS

30 Aircraft 14 NMCMU NMCMS

31 Aircraft 15 TNMCM TNMCS

32 Aircraft 15 NMCMU NMCMS

33 Aircraft 16 TNMCM TNMCS

34 Aircraft 16 NMCMU NMCMS

35 Aircraft 17 TNMCM TNMCS

36 Aircraft 17 NMCMU NMCMS

37 Aircraft 18 TNMCM TNMCS

38 Aircraft 18 NMCMU NMCMS

39 Observations Notice the relative contributions to downtime from supply and maintenance, and the contributions of scheduled and unscheduled maintenance. In every case, maintenance contributes more to downtime than supply In every case, unscheduled maintenance contributes more than scheduled maintenance We, the Air Force, have made a concerted effort to go after supply and scheduled maintenance

40 Data Unscheduled maintenance means that something failed Is it important to know when things fail? ABSOLUTELY! In most cases, engineers only find out about things that fail if they re not covered by the TO

41 Risk Management In order to manage risk, you have to be able to determine risk To determine structural risk, you have to know: Crack length Crack growth curve Equivalent Initial Flaw Size (EIFS) distribution determined from aircraft condition data Loads applied Exceedance curves Residual strength Probability of Detection of NDI Without current aircraft condition data, you don t have a chance!

42 Risk Data Rather than make up data, we issue a hair on fire TCTO to get data It s much more efficient to collect and keep data on an ongoing basis

43 Example C-5 Aft Crown Skins Stress Corrosion / Fatigue cracking Generated crack growth curve from known data point Performed risk assessment Shows risk approaching unity for current time Only one large crack found to date Obviously the crack growth / risk is wrong, right?

44 Not Necessarily! Example (Con t) How many stress corrosion cracks have been found and repaired IAW TO 1C-5A-3 that we don t know about? A lot! Any of these could have grown into a large crack if undetected / unrepaired Risk curve could be correct, just mitigated by repair Difficult to persuade MAJCOM to act without believable risk categorization

45 Consider Data Management Up Front How many other Crises could have been averted if data had been available to detect / predict trends? Plan up front to collect and store maintenance data What do you need to capture? Inspections performed, results, repairs, R 2, etc. Detailed description of deficiencies with pictures How are you going to analyze it? Plan it into the system so that it s easy for the technician to give it to you