WASHINGTON — The Air Force has grounded most of its older C-130H Hercules cargo planes and variants due to a problem with their propeller barrels.

Air Mobility Command on Friday confirmed a wide swath of its C-130H fleet, which numbered 128 at the beginning of fiscal 2022, is unable to fly, and it’s unclear how long it will take to replace all the defective propeller assemblies.

AMC said 116 C-130Hs, including variants of the mobility aircraft, were grounded on Tuesday due to concerns their propeller assemblies are defective, and that inspections over the coming days will show how many of those are affected.

AMC said the groundings are “widespread” and primarily affect the Air Force Reserve and Air National Guard.

The unofficial Facebook page Air Force amn/nco/snco posted a screenshot of a time compliance technical order on the groundings Wednesday. On Friday, the page posted a screenshot of a slide that said the propeller barrels in question had been installed in 100 C-130Hs, as well as the entire inventories of eight MC-130H Combat Talons, seven EC-130H Compass Calls, and one TC-130H.

In a statement to Defense News, Air Mobility Command said a maintenance crew at Warner Robins Air Logistics Complex in Georgia found a persistent leak coming from a C-130H propeller while test running the plane’s engine after it had undergone depot maintenance.

That propeller assembly was removed and sent to the complex’s propeller shop, AMC said, where a technician found a crack in its barrel assembly.

Further inspections found two more propeller assemblies had the same problem, Air Mobility Command added.

AMC ordered immediate field level visual inspections on all C-130Hs with the older 54H60 model propeller, and then conducted metallurgical reviews and stress analyses, the command said. After those reviews, Air Mobility Command issued another order to immediately replace problematic propellers.

The command said newer C-130Js and C-130Hs that have already had their propeller assemblies upgraded with the eight-bladed NP2000 system are not affected by the order.

This is the second time in more than three years that significant numbers of C-130Hs were grounded due to propeller problems. In February 2019, the Air Force grounded 60 C-130Hs — at the time, nearly one-third of the fleet — for several weeks due to concerns their pre-1971 propeller blades could crack. Those C-130s had their propeller blades replaced over subsequent weeks.

Stephen Losey is the air warfare reporter for Defense News. He previously covered leadership and personnel issues at Air Force Times, and the Pentagon, special operations and air warfare at Military.com. He has traveled to the Middle East to cover U.S. Air Force operations.

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