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Investigation: Sea Dragon Crash Result of Mechanical Fault

MH-53E from Mine Countermeasure Squadron 14 "Vanguard" (HM-14) in 2006. US Navy Photo

MH-53E from Mine Countermeasure Squadron 14 “Vanguard” (HM-14) in 2006. US Navy Photo

The U.S. Navy has released the Judge Advocated General report for a Jan. 8, 2014 crash of a MH-53E Sea Dragon earlier today. The report concludes that the crash was the result of a mechanical problem rather than any fault on part of the crew.

The aircraft, which was towing a MK-104 acoustical device while flying 100 feet above the ocean, crashed 18 nautical miles off the coast of Virginia Beach, Va. Both pilots and a crewman were killed in the accident.

The Navy investigation concluded that fire broke out in the upper left wall of the crew cabin, filling the aircraft with black smoke. The pilots, who were flying blind due to the smoke, became disoriented and subsequently crashed.

“Post-mishap engineering investigations of the salvaged aircraft concluded that chafing between insulation covering electrical wires and the surface of the aluminum fuel transfer tube had likely enabled an electrical arc from a wire to breach the transfer tube, igniting the fuel that was inside,” reads the report.

The Navy has completed all of the recommendations that came out of the accident report except for inspecting the wires in question. There are 20 MH-53E that still need to be inspected. But thus far, 18 percent of the MH-53 fleet has shown chaffed wiring—28 helicopters out of 153 aircraft.

The Navy is expected to release a new inspection schedule for the wiring in the next three to four months.

  • publius_maximus_III

    If the pressurized aluminum fuel transfer tube had been made from a non-counductive material, this tragedy would not have happened.
    Even if the same chaffing had breached a non-conductive tube material, and caused the same type of spraying leak, there would not have been an electric arc present to ignite the plume that cause the billowing smoke. The simultaneous presence of a leak and an arc caused this crash. Remove one or the other condition and this Sea Dragon crash would not have occurred. The Navy should consider making such changes to any exposed fuel lines inside a cockpit interior.
    My condolences to the families of the service men lost.

    • USNVO

      Not true. Even if the tube was non-conducting, the skin of the aircraft isn’t, so you still end up with arcing and a fire. It maybe takes a little while longer, but once you have a fuel leak and arcing, you are going to get a fire. Also, while the fire started due to arcing, that does not mean that there are not other ignition sources that wouldn’t have caused the fire besides the arcing.

      Any material has to meet literally hundreds of requirements including weight, strength, heat resistance, fatigue, machinability, cost, damage tolerance, compatibility with other materials, lighting resistance, corrosion resistance, etc. So minimally reducing an arcing problem may actually dramatically increase other risks.

      • publius_maximus_III

        Not true, -your- Not true, sir.
        .
        The chaffing action broke down the wiring electrical insulation and exposed the arc source, a live electrical conductor inside. That chaffing did not breach the wall of the aluminum tubing with pressurized fuel inside it. Spit in one “aluminum hand” (mechanical chaffing) and micturate in the other “aluminum hand” (an electrical arc capable of burning through aluminum like it was a piece of paper) and see which hand fills up first.
        .
        An electrical short against the aluminum skin might have burned a hole through to the outside of the cockpit, no big deal. An electrical short against a hole in an aluminum tube with pressurized fuel inside it could become just what one crewman reported: a flame thrower — VERY big deal.
        .
        I stand by my original post. If the tube material had been non-conductive, there would have been no arc and therefore no fire. A fuel leak caused by chaffing of a non-counductive fuel line would have been very gradual, could have been detected before it caused a fire, and the transfer line isolated. The instantaneous spark-fuel combination caused by breach of a conductive aluminum fuel line provided no such reaction time — Arc, Leak, Ignition, Flame Thrower.
        .
        Doubtless there are all sorts of compromises necessary when chosing materials for such a complex machine being built by the lowest bidder. The safety at issue here suggests a rethinking of some of those compromises. A hose is the most likely substitute for tubing. Hoses must be periodically replaced, but please understand that aluminum (unlike steel) has no fatigue life endurance limit.

  • Secundius

    SHOULD’VE, WOULD’VE, COULD’VE. Nothing but the best for our boys, Yeah, Right.
    An OXYMORON, if I’ve ever heard one!!!

  • OLD GUY

    TRAGEDY. INSPECT, MAINTAIN, INSPECT, MAINTAIN, INSPECT, MAINTAIN.