An RAF F-35B crashed last November because one of the engine intake plugs was left in. The U.K.’s Defence Safety Authority publicly released an interim report that was sent up the chain of command last June mainly to assure the brass that the plane itself wasn’t likely to blame for the mishap. “Based on the evidence obtained, the Panel is confident that the primary causal factor of the event was the left-hand intake blank remaining in the aircraft prior to launch reducing the engine power,” the report said. “This was most likely due to a combination of human, organizational and procedural factors.”

The aircraft was set up to launch in short takeoff mode from the deck of the HMS Queen Elizabeth II carrier on Nov. 21. The ship had just transited the Suez Canal and was operating in the eastern Mediterranean. All the run-up checks were normal but when the pilot hit 97 percent power for takeoff, the engine lagged and showed only 74 percent power. The pilot firewalled the throttle but still didn’t get takeoff power. He tried to abort but didn’t have enough deck left and he ejected. He landed safely back on the deck. The plane went off the ski jump ramp and, as it sank, the intake plug floated free. Crews grabbed the plug, but the plane went to the bottom and was recovered later.

Russ Niles
Russ Niles is Editor-in-Chief of AVweb. He has been a pilot for 30 years and joined AVweb 22 years ago. He and his wife Marni live in southern British Columbia where they also operate a small winery.


  1. Similar thing happened to me on an F-111 during an alert exercise. My new crew chief had his training cut short (pencil whipped) and stood to the right front of my jet and signaled that the right engine was clear to start( with the engine cover still in). The blow-in doors let enough air in to start. Fortunately only minor damage was done, but I, being the aircraft commander was blamed though I did nothing wrong.

    • Yeaaaa…no. It was your aircraft, mate. Spoken as another former Vark driver who sat Victor Alert at the ‘Heath. Your crew chief may have had the authority to remove that red gear from your aircraft but the responsibility to ensure that it was safely configured for start/taxi/takeoff was and remained yours. Don’t misunderstand, s/he was not blameless but with greater power (and pay) comes greater responsibility.

  2. I was a crew chief for six years on three different USAF jet fighters. After my preflight was complete the pilot would show up with checklist in hand and we completed a second walk around. All the USAF pilots that I crewd for were extremely through and never have missed an intake plug. Guess things have changed.

  3. Similar to the Singapore Airlines A350 in Brisbane, Australia last spring that was about to push back with its pitot covers still on. Here’s an excerpt from the Australian Transportation Safety Board report.

    (And we all know about that word “ass-u-me”).

    Failures in pre-flight procedure

    At 07:32, the AME (apprentice maintenance engineer) placed covers on four pitot tubes – a common practice at Brisbane Airport due to the threat of mud wasps nesting inside the tubes. At 08:52, the flight’s first officer, not the LAME (licensed aircraft maintenance engineer) or AME, conducted a pre-flight walk-around as the LAME attended to a nearby aircraft.

    According to the ATSB report,

    “The walk-around was truncated from the nose, to the right engine, across to the left engine and back to the airbridge. The aircraft operator’s procedures also required the extremities of the wings, airframe, and tail section to be inspected; however, this was not carried out. The captain looked up at and likely observed the fitted pitot covers, however they were required to be fitted at that time as per the operator’s policy.”

    The LAME returned to the Singapore Airlines A350 at 08:59 and entered the flight deck, removing a pitot cover warning placard they had placed there earlier.

    The report added,

    “The LAME stated that they had not verified that the pitot covers were removed, or requested that the AME remove the pitot covers, but assumed that they would have been removed by that time.”

  4. This was obviously a design and engineering failure to not for see this occurring and address this accident waiting to happen. Manufacturer is responsible….Just repeating what several others summarized about the control lock design in the SIAI Marchetti he crashed.

    • The cowling air intake plugs on my engine are connected by a sturdy strap that loops around the prop. In thirty years of engine starts it has needed to do its job only once. That’s the value of thoughtful design and manufacturing: anticipation of the consequences of an inevitable failure in wet-ware.

      • Yeah, that only works if the pilot properly inserts the plugs. When I walk around at places like Oshkosh, I’m always amazed at the number of plugs with the rope hanging under the prop.

  5. On a side story, the cash strapped Russian military command just sent a large shipment of Intake Plugs to the UK.

    • The accident made the news back then. This article is about the interim report about the cause. This report was recently released to the public.

    • I must say, that is one sturdy (and expensive) cowl plug! I would have thought it would have been sucked into the engine. A $100 million dollar airplane destroyed buy a $10 dollar chunk of foam!

  6. help me understand this:
    pilot “hit 97% power” was this rpm? EPR? some new instrument?
    engine only “75% power.” is this all telemetry? how do they know? or an FDR after recovery?

  7. Sorry, but that slow start of the roll would have alerted any “woke” pilot to a problem. But just to think it will get batter later down the deck, only to blow the canopy right at the edge. That is some sleepy crews there.

  8. Don’t they have to go to full power before release of brakes? I would have thought the pilot would have noticed a power issue before brake release.

  9. Those cowl plugs will get you if you don’t watch out. I used to have a client with a twin-jet corporate airplane with tail mounted engines. One time on a trip, the pilot had the “smiley face” covers put on the engines. The boss came back early and was in a hurry to get going so the pilot did an abbreviated walk-around and missed that the right cover was still in place. When he attempted to start that engine, the cover got sucked in, damaging the engine. The less than forgiving boss fired him on the spot.