1 / 16

By Salvatore Piu

By Salvatore Piu. Navy Landing Gear Perspective Tribaloy-Treated F/A-18C/D Main Gear Shock Absorber. August 2001 HCAT mtg. F/A-18A-D Main Landing Gear Tribaloy T-400 - Treated Shock Absorber. Issue Proposed modifications Tests and flight evaluation Status. Issue.

bunme
Download Presentation

By Salvatore Piu

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. BySalvatore Piu Navy Landing Gear Perspective Tribaloy-Treated F/A-18C/D Main Gear Shock Absorber August 2001 HCAT mtg

  2. F/A-18A-D Main Landing GearTribaloy T-400 - Treated Shock Absorber • Issue • Proposed modifications • Tests and flight evaluation • Status

  3. Issue • Severe wear/scoring found on cylinder and piston at overhauls: • Currently replace 100% Piston Rings (P/N 74A410855-2001/-7001) and Snubber Rings (P/N 74A410611-2001/-7001 • Currently replace @ 90 % Piston Heads (P/N 74A410853-2003/-7001)

  4. Shock Absorber ConfigurationP/N 74A410850-1009 • Two stages • Low pressure chamber, 150 psig, 8.87 inch stroke (shown in blue) • High pressure chamber, 1265 psig, 4.25 inch stroke (shown in green) • Total Stroke: 13.12 inches

  5. Proposed Modifications • Purpose: • Reduce wear and internal damage of parts that typically get scrapped when worn -> increase time between overhauls • Changes: • Piston ring & snubber ring material change: from hard anodized aluminum to beryllium copper • Piston head treated with Tribaloy SWA UHP-180 T-400 HVOF-deposited coating • Tribaloy 400 Treated Area: • Not the main piston area typically treated with Hard Chrome • On an area where no previous coating applied

  6. Piston head

  7. Potential Benefits • Increased MTBF • Improved fleet readiness • Longer component life • Reduced overhaul costs • Increased safety

  8. Tests and Fight Evaluation • Two shocks modified, S/N EMC 0632 & EMC 0635 • Lab Tests • Shock absorber ATP (service pressure) • Load-stroke tests (verify consistency of static, load-stroke performance)

  9. Tests and Flight Evaluation • Flights • Both shocks installed on product support plane (at Boeing, St. Louis, October, 1997): 23 flights (31 touchdowns) • Performed post-flight load/stroke test (replaced leaking schroeder valve) • Both shocks installed on one in-service aircraft (May 5, 1998) • Request @ 30 CV arrested landings to provide meaningful data • Flight clearance limited to 40 CV arrested landings • Extended flight clearance to avoid interfering with fleet operations • Right main landing gear experienced planing mechanism failure with EMC 0635 ( 60 field landings, 13 FCLP, & 80 CV arrested landings • Removed both shocks immediately after planing mechanism failure

  10. Tests and Flight Evaluation • F/A-18A-D Planing Mechanism • Function: plane the main wheel axle and compress the gear (shock absorber) to fit in the wheel well • System has historical failures • 8 primary components in system • Improperly functioning shock is a suspect contributor to failures

  11. Tests and Flight Evaluation • Teardown inspection: shocks in excellent condition • Goal reset by Navy: 200 CV landings • Inspected, serviced, and placed shocks back on a fleet aircraft • Shocks on various aircraft from May 99 to June 00 • Modified shocks both participated in planing mechanism failures • For each planing mechanism occurrence, shock removed from the failed gear, inspected, re-serviced, and placed on a fleet aircraft • 5 on MLG’s with EMC 0635 (3 different MLG’s) • 1 on a MLG with EMC 0632 (one of the MLG’s previously failed with EMC 0635)

  12. Status • Flight Evaluation • Achieved 200 CV arrestments with one shock • Personnel associate modified shocks with planing mechanism failures due to repeated participation • In-service fleet evaluation halted by US Navy • Teardown inspection: • Wear observed was considerably less than would be expected (based on usage & compare to previous overhauled shocks)

  13. Status • Notes: • EMC 0635 participated in 2 planing system failures, not included in qty (5), prior to Triballoy-associated modifications. • Aircraft with modified shocks squawked for a pause in the stroking of the landing gear during landing (EMC 0635 lab tested for cause: nothing found) • EMC 0632 exhibited slow to extend characteristics prior to modifications

  14. S/N EMD 0635: Piston Head & Ring

  15. S/N EMD 0635: Cylinder

  16. Current Plan • One Additional Flight Evaluation • One aircraft with one new shock and and new-modified shock • 200+ CV & FCLP landing • Tear-down and compare both shocks • If no issues found, implement change to spares and normal overhaul of existing shocks

More Related