Home » Aviation » Navy’s P-8As Unaffected by FAA’s Boeing 737 Engine Inspection Requirement After Fatal Southwest Incident


Navy’s P-8As Unaffected by FAA’s Boeing 737 Engine Inspection Requirement After Fatal Southwest Incident

Aviation Machinist Mate 1st Class Joseph Ihrig, left, and Aviation Machinist Mate 2nd Class Miko Brandon, right, both assigned to Patrol Squadron (VP) 4, perform a fan blade loop inspection on a P-8A Poseidon aircraft onboard Naval Air Station Whidbey Island’s Ault Field on Dec. 6, 2017. VP-4 is currently conducting its Fleet Readiness Training Plan in preparation for their upcoming deployment. US Navy photo.

The Navy’s fleet of P-8A Poseidon aircraft are not in any immediate risk of facing the same engine failure that caused the April 17 emergency landing of a Boeing 737 – which the P-8 design is derived from – a Navy spokeswoman told USNI News.

The Federal Aviation Administration on Friday issued an emergency airworthiness directive mandating that any plane whose CFM56-7B engine had conducted more than 30,000 takeoff-and-landing cycles must be inspected within 20 days. This would affect 352 engines in the U.S. and 681 engines worldwide, according to the FAA statement.

However, the Navy’s P-8s are not among them. Though the P-8 – which is built on the same 737 production line as the commercial planes but then pulled aside for the addition of military-specific gear – uses the same CFM56-7B engine, “there is no immediate risk to or action to be taken by the P-8A community. The Navy’s P-8A engines remain well below the cycle limit for required inspections of fan blades,” P-8 program office spokeswoman Denver Beaulieu-Hains told USNI News today.
“The FAA mandates inspection [for commercial aircraft] to start at 20,000 cycles, while the current high-time P-8A has accrued 5,175 cycles (as of 13 Apr 18) since it entered service in 2012. At the current cycle rate, the first engine in the P-8A fleet will hit the 20,000 cycle point in about 10 to 15 years.”

Lt j.g. True Jones, a pilot assigned to the “Skinny Dragons” of Patrol Squadron (VP) 4, climbs aboard a P-8A Poseidon aircraft at Naval Air Station Whidbey Island’s Ault Field during a routine maintenance check on Jan. 22, 2018. US Navy photo.

Beaulieu-Hains said that Naval Air Systems Command had previously determined that the P-8 engines’ fan blades – the component that failed in the Southwest Airlines Flight 1380 incident at more than 30,000 feet altitude that killed one passenger and forced an emergency landing – would be inspected when the planes are brought in for their first scheduled depot maintenance visit, which would occur “no later than the 6,000-cycle threshold, with a recurring 6,000-cycle inspection interval through 20,000 cycles. After 20,000 cycles have accumulated, the engine will be inspected at a 3,000-cycle interval,” she said.

Boeing has sold its P-8A to the U.S. Navy, the Royal Australian Air Force and the United Kingdom Royal Air Force, and its P-8I variant to the Indian Navy. The Navy has 64 planes in its inventory as of January and is slated to buy 111 total, according to NAVAIR.

  • Secundius

    Comparing the CFM Int’l CFM-56-5 Turbofan of a P-8A to that of a F108 (737), is like comparing a 7.62x51NATO to a .308Win. Visually they look the same, but under the skin there “Two Different Beasts”. The CFM-56-5, was specifically designed to use DAAK 7-87-C-0043 “Belvior” (i.e. NDF F-76) Fuel, while the F108 wasn’t. Belvior would probably KILL a F108 turbofan…

    • Rocco

      What’s the difference?? Jet-A & JP-5 are the same thing basically.

      • Secundius

        Belvior is refined and blended from “Shale Oil” not “Crude Oil”. Even Military Grade Lubrication is Belvior based. It’s away to assure Quality Control of the Fuel and has a Longer Storage Life than Crude Oil based Fuels…

        • Jon Tessler

          if this was a fuel issue i would agree with you, but fan blades don’t fail due to fuel, they fail because microscopic cracks in the metal are not found through Xray examination.

          • Secundius

            I never claim it was the Fuel! USNI News is comparing a Civil Aircraft’s F-108 Turbofan to that of the Poseidon CFM-56-5 Turbofan, and Ruling out Any Similar Problems. Turbofans just don’t “Fragment” in Flight without a reason! I’m suspecting Bad Maintenance or Bad Fuel and I don’t recall a “Bird Strike” in the report…

    • Graeme Rymill

      Differences between a commercial CFM56-7B and the Navy version:

      The Navy version “makes room for the bulkier 180kVA integrated drive generators (IDG),
      one for each engine, that the US Navy needed for its mission. The Boeing 737-800, on which the P-8A is largely based, uses 90kVA generators. Other differences between the commercial and military variant of the engine, CFM says, include a strengthened accessory gearbox to suit the larger IDG, “slight” adjustments to the electronic engine controls software for several control schedules to accommodate the larger IDG load, and minor configuration changes to harnesses and support brackets to handle the 180kVA upgrade.”

      Two different beasts? Not really.

      • Secundius

        The CFM=56-5 is designed to burn “Belvior” while the F108 Isn’t. The 7.61x51NATO and the .308Win are virtually identical, yet the 7.62x51NATO has a Greater Propellant mass than the .308Win…

        • Graeme Rymill

          As the article above states the Poseidon P-8A’s engines are CFM56-7B series not CFM56-5 series as you have repeatedly claimed. In your previous reply you mention ” ‘Belvior’ (i.e. NDF F-76) Fuel”. F-76 fuel “is the MIL-SPEC distillate fuel normally used in shipboard diesels, gas turbines, and boilers.” It isn’t used as an aviation fuel. Other than the minor changes I have listed in my other reply the engines used by the P-8A are the same as those used on commercial 737-800 aircraft.

          • Secundius

            Guess what! Military helicopters and tanks also run on the Stuff…

          • Graeme Rymill

            The United States Navy uses JP-5 fuel for its shipboard helicopters not F-76. As the 2014 Aircraft Refueling Handbook For Navy/Marine Corps Aircraft notes JP-5 “is the only fuel that can be used for turbine engine aircraft aboard ships and is used widely at USN and USMC air stations”.

          • Secundius

            What part of “Also” didn’t you get. I left the US Army in 1981, and was refueling AH-1S Tow Cobra’s with “Belvior” for at least a Year before I left…

          • Graeme Rymill

            Fascinating! Unfortunately though the discussion is about a USN plane – the Poseidon P8-A and the fuel it uses. I will correct my statement – “F-76 isn’t used as an aviation fuel by the USN” Happy now?

          • Secundius

            The Military Version of the Civilian Engine was “Specifically Designed” to use “Belvior” as a Fuel. Where in ANY of my Comments did I say that Belvior was Widely Distributed in the US Military?

          • Graeme Rymill

            We will have to agree to disagree as further argument is pointless

          • Secundius

            In other words, you leapt to a conclusion to a meaning that wasn’t actually said…