F-16 Accidents

USAF F-16A #78044 with its LEF upwards. The pilot [USAF photo]


  • Anonymous on 2004-Oct-26 20:27:27 Anonymous said


    Seen that before....someone didn\'t rig the PDU correctly......OOPS!
  • Anonymous on 2004-Oct-30 22:04:45 Anonymous said


    No way that thing flew like that soon as hydraulic pressure is applied they would have done that if incorrectly rigged or it if it did happen in flight not done to rigging major internal failure of the PDU.
  • Anonymous on 2004-Nov-01 11:30:48 Anonymous said


    how the hell he flew this thing
  • Anonymous on 2004-Nov-04 15:19:16 Anonymous said


    rotory actuator failure usually causes this type of thing.
  • Anonymous on 2004-Nov-05 10:56:30 Anonymous said


    Do you really think all 4 actuators failed at the same time MrFalconfixer?
    1 of the 2 shafts from the PDU to #1 act. failed and what happened to the assymetry brake?
  • Anonymous on 2004-Nov-20 18:25:39 Anonymous said


    One hell of a spoiler effect though....
  • Anonymous on 2004-Nov-21 14:47:26 Anonymous said

    William G The B-Shop Guy

    Actually saw the same thing happen before
    that one was a Mac Dill bird, Blue Section 62nd TTS, The failure was the LEF PDU, allowed the free rotation of the LEF up to almost 80 degrees.
    The Asymetry Brake did lock out but the Asymetry Brake Torque Shaft was twisted like a barberpole.
    The pilot was on his first night solo flight and when this happened he experienced an uncomanded roll to the left. He punched the wing tanks and the Right tank did not separate. With the right tank still on the airframe it gave enough of an imbalance to counteract most of the roll, so that he only had to dial in full trim and a little stick pressure.
    After landing he got out of the jet and kissed the ground.
    I was kinda shocked to have seen the damage and the fact that he flew back safely and landed.
  • Anonymous on 2005-Jan-25 22:23:42 Anonymous said

    Mike Kopack

    I can confirm the from William G about the incident at MacDill. Was a Crew Chief with the 63TFTS at the time and saw the aircraft after recovery.
  • Anonymous on 2005-Mar-10 18:04:18 Anonymous said

    falcon fixer

    I had seen this happen before, rotary actuator failure, and torque tube failure at the pdu. At the time the assymetry brakes were not connected the cannon plugs were shorted out. this was because of numerous assy brake failures.
  • Anonymous on 2005-Mar-29 04:31:23 Anonymous said


    What block is this? You gotta look at the big picture. Was the LE R/R? Was it at depot most PDU work is done in depot.Did the crew cheif suck and manage to gay up the assymetry breaks. it's an f-16 no matter what the deal is 781s would give a solid lead to why it happened. I'm just glad LE flaps are easy to change out. If you read the GS those angle gearbox has alot of torque. this is a multiple factor incident.
  • Anonymous on 2005-May-19 12:10:40 Anonymous said


    naaa thunder, they seem to like to do that down at the 4th. that also happened down at the 4th during my two year stint at hill...
  • Anonymous on 2005-Aug-07 18:26:36 Anonymous said


    Block 1, 5 and early 10's all suffered from this issue. Might be wrong, but don't think they even had assy brakes until midway thru the block 10 and they still had issues which is why we flew with them disconnected for a time. Most of these were attributed to internal PDU failure (shear) at which point the flap rolled over or under dependent upon airflow at the time of shear - least that's my recollection.
  • Anonymous on 2005-Aug-12 07:17:21 Anonymous said


    Looks like the comman servo was 25 down when they hooked up the tubes
  • Anonymous on 2006-Jul-13 17:19:44 Anonymous said

    78-0044 LEF Problems?

    'Believe this picture is of a 421st Blk 10 aircraft back in late 1981/early 82; due to the fact that 78-0044 (Blk 5 then) had a black radome. Yeah, sure, the picture is black-n-white, but the 421st had the top black stripe with red hour glass (only) tail flash during this timeframe (notice background aircraft on ramp).
    Incident happened on final approach with pilot experiencing heavy yaw thought to be caused by heavy crosswinds (frequent at HAFB). Aircraft landed safely w/o incident and pilot notified of occurance by EOR groundcrew. Upon inspection, RH LEF Angle (Bevel) Drive Gearbox Torque Tube bolt was found missing and torque tube simply came off spline shaft. Only damage was to the top RH LEF Seals; believe we quickly returned the a/c back to service with same LEF. At the time, all Asymmetry Brakes were either removed or cannon plugs disconnected. Outcome of investigation: new requirement for .002-.010 (freeplay) bolt clearance checks (a QA favorite) and presence of cotter keys on all LEF torque tube bolts (both requirements did not exist in JG27 before incident).
    DCA (421st Crew Chief Sep '80- Nov '82)

  • f4dj79 on 2012-Jan-04 15:33:58 f4dj79 said


    I saw many things at HAFB during my 1976-1980 tour. Nothing surprises me!! I now work for Boeing on the 777 program and mechanics still make the same mistakes. I am very familure with the F-16 leading edge installation and rig. The fact that one single bolt left out of the installation could cause this problem, believable. The first few years of the F-16 at HAFB were interesting, The Air Force bailed GD out on many problems. It is funny and tragic that we always write procedures to fix things after they have failed. Maybe some day the aircraft makers will do some thing like fully test assy's by haveing the mechanics take it apart and put it back together and use the instructions as written to see if first it can be done, and there is new extra parts left over.
  • Bob on 2012-May-01 21:22:01 Bob said

    Another take

    I was in the 16th TFTS when this happened. Some time before we had a mishap due to failed splines on a torque tube. Since at the time the assymetry brakes had been removed on all out jets, there was no fail safe as a result. Because of the mishap, we performed a 100% inspection of torque tubes. I'm sure maintenance was rushed to get them done (big surprise). As with a lot of rushed things, mistakes do happen and a cotter pin was not installed. Kind of like the gun port cover that departed a Block 40 jet ar RS because the cover was installed and safety wired, but the nuts were missing....
  • creel on 2012-Jun-27 08:24:42 creel said

    I've seen it too, it still happens all the time, but doesn't cause any damage if all of the upper leading edge flap seals are all off, someone rigged the PDU wrong, it was sitting at 25 degrees down while the flaps were at zero

This image is also used in

  • Aircraft Database: F-16 #78044

    In Lt. Col. Pat "Gums" McAdoo's words:

    "I was the first Viper pilot to successfully land the thing with a failed leading edge flap. Was early spring/late winter 1982. Maybe 20 March, tail number 044, as that log entry shows 0.3 hours and a precision approach. Weather was not ll that keen. Have the HUD video in VHS format."

    "Maintenance troops had failed to insert a 'keeper' bolt that is supposed to keep the flap drive tubes from slipping apart. It's like a cotter key on a bolt. The flap drive motor has a spline gear on it and the drive tube has gear teeth that match up. So the drive tube gradually slipped out from the motor spline gear. When I rotated, the drive tube slid all the way out and the leading edge flap went up until the wing upper surface stopped it. Maybe 50-60 degrees. Another troop had his fail a few months later and the flap went to 90 degrees because he was going a lot faster when the drive tube failed. So I was at 160 knots and holding full left stick. Post-flight data revealed that I had about one pound of control authority for banking left. So I was holding 15-16 pounds of left stick the whole time. "

    "I stayed at 170-180 knots, as I could still maintain control and wasn't gonna play Chuck Yeager more than I had to. Nevertheless, I was the first troop to fly the thing in that configuration, so everything was new territory. Bunted over to get opposite flap 2 degrees up and locked the flaps( LEF's go up when bunting over, or when weight is on wheels). I now had both LEF's up, and it seemed to help with the roll authority. Additionally, that other flap wasn't gonna be moving all over the place, and this kept things a little more predictable. "

    "Came around on the ILS and landed in one helluva crab. The drag was so great that I almost landed short when I pulled off the power. As I was coming in a lot hotter than normal, I thought I would land long. heh heh, sucker dropped like a rock and I was able to make a mid-field turn off."

    Exact date of this mishap is not known, but did happen in 1982.

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