Transition from PDM to HVM in the works, but will take time Published Sept. 3, 2009 By Ed Drohan 78th Air Base Wing Public Affairs ROBINS AIR FORCE BASE, Ga. -- Even as the High Velocity Maintenance team is validating their processes and procedures on a C-130 for the first time, they're still working on the big question. "How do we get there from here?" The plan is to eventually transition all C-130s from the current Programmed Depot Maintenance process to High Velocity Maintenance, but that transition won't happen overnight, especially since the two processes are so drastically different. Under PDM, aircraft are inspected and necessary repairs and modifications made at Robins every five years in a process that takes more than four months per aircraft. The aircraft must also undergo a two-week isochronal inspection at their home station every 18 months. With HVM, those aircraft will come to Robins every 18 months, where only one section of the aircraft at a time will undergo necessary repairs. The isochronal inspection will be done at the same time, freeing up those two weeks at home station and letting maintainers know the condition of the aircraft prior to its next visit here. All told, HVM experts hope to reduce the amount of downtime for each aircraft from four to five months to 39 days. But how you go from one system to another is what HVM team members have been working on for more than a year now. The solution to that problem, said HVM Team member George Barnes, is a process called PDM-T, or Programmed Depot Maintenance-Transitional. Mr. Barnes is a contractor with Simpler Consulting working with the 560th Aircraft Maintenance Squadron. With PDM-T, aircraft will go through a partial PDM along with the HVM. Just how much of the PDM is performed is determined by how long it's been since the aircraft's last PDM, Mr. Barnes said. For example, if it's been three years since the plane's last PDM, we'll bring it in, do one of the HVM processes and also do a partial PDM, Mr. Barnes said. The aircraft will then return in 18 months for another HVM process and, if necessary, another partial PDM. "If it's been five years since the last PDM, the first time we might do the HVM and three-quarters of a PDM," Mr. Barnes explained. "When it comes back in 18 months we'll do another HVM process and maybe half a PDM. The third visit will be all HVM." If the aircraft has been through a PDM cycle more recently, the number of visits and partial PDM extensiveness could be less, he said. The physical aircraft inspection is a critical part of the HVM process since it allows maintainers and sustainers to know the condition of the aircraft so parts can be ordered and on-hand for the next visit, and plan for the order in which the work should done, Mr. Barnes said. The partial PDM will take care of that, but the inspection could be done at the aircraft's home station if the aircraft completed a full PDM more recently. Barnes said the entire transition process is expected to take about four years before every aircraft in the C-130 fleet is on the HVM cycle.