Bearhawk Aircraft Bearhawk Tailwheels LLC Eric Newton's Builder Manuals Bearhawk Plans Bearhawk Store

Announcement

Collapse

Guidelines for this Section

Please post thoughtfully in this section. Create/maintain one thread per mishap. Focus the discussion on the event, and learning from it, rather than on the individuals. Keep in mind that any damaged Bearhawk may represent many years of lost work, many thousands of lost dollars, injury, or worse. Create posts that will enhance safety of the Bearhawk fleet and educate other Bearhawk operators. It is not always easy for someone to come forward after a mishap, be tactful and don't make someone regret admitting a mistake.
See more
See less

2022 n964rs

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • 2022 n964rs

    On October 29, 2022, about 1452 eastern daylight time, an experimental, amateur-built Bearhawk Patrol airplane, N964RS, was substantially damaged when it was involved in an accident near Hanover Township, Pennsylvania. The pilot and pilot-rated passenger were fatally injured. The airplane was operated by the pilot as a personal flight conducted under the provisions of Title 14 Code of Federal Regulations Part 91.

    Witnesses reported that the pilot and pilot-rated passenger departed Farmers Pride Airport (9N7), Lebanon County, Pennsylvania, earlier in the day. They flew to the Hazleton Regional Airport (HZL), Hazleton, Pennsylvania, then on to the Wilkes-Barre Wyoming Valley Airport (WBW), Wilkes-Barre, Pennsylvania. At WBW, the pilot told a friend that the airplane had a rigging issue that seemed to cause the airplane to “kick” laterally during turns. He suggested that his friend fly the airplane to see what he thought. The friend performed a 10-minute flight and reported that he noticed the odd yawing moment in the turns. The pilot responded that he would address the issue “this winter.” After lunch and fueling the airplane with 30 gallons of fuel the pilot and pilot-rated passenger intended to return to 9N7. Witnesses reported that the pilot sat in the front seat and fastened his seatbelt and shoulder harnesses while in their presence.

    Preliminary Automatic Dependent Surveillance-Broadcast (ADS-B) data revealed that the airplane departed runway 25 at WBW about 1448. After departure, the airplane turned slightly left, flew in a southwesterly direction, and climbed to an altitude of 1,700 ft mean sea level (msl). The recorded data indicated a 35-second level-off, followed by a descent to about 1,500 ft msl where the airplane’s altitude varied slightly over a couple minutes. In the final seconds of the flight, data indicated a 400-ft descent in fewer than 2 seconds. Witnesses reported that the airplane “rolled” then “bucked” as its nose “dipped down initially,” then pitched up “quickly.” At this time, they reported the pilot was out of the airplane. Other witnesses reported that they heard a loud impact then noticed the pilot “spiraling” down and the airplane pitched downward and descending to the ground.

    Examination of the accident site revealed that the airplane impacted a grass field in a near vertical nose down attitude about 5.2 nautical miles southwest of WBW. A linear ground scar, consistent with the length of the left wing, radiated from the center of the wreckage with the scar oriented toward a magnetic heading of 338°, and the wings came to rest oriented on a magnetic heading of 319°. All major airplane components were located on site; paint chips, the airworthiness certificate, and portions of the cockpit ceiling or side window Plexiglas were recovered about 1,900 ft from the main wreckage, followed by a portion of a tail rib at 900 ft. The pilot was located 530 ft from the main wreckage.

    Examination of the wreckage at the accident site revealed that the airplane was composed of a fabric covered steel tubular fuselage and tail, and an aluminum strut braced wing. Both wings were accordion-crushed aft and remained attached to the fuselage, which came to rest adjacent to the right wing. The tube structure around the cockpit area was cut by first responders and mostly open, with the control panel displaced forward toward the engine compartment. The airframe structure aft of the cockpit was intact to the tail area, where the forward attachments of both the vertical and horizontal stabilizers were fractured. The tail section was largely destroyed, except for the left horizontal stabilizer, which had its elevator with elevator trim tab intact. The engine was partially attached to the engine mounts and embedded in an impact crater. The propeller hub remained attached to the crankshaft flange, and both propeller blades were impact separated from the propeller. A ground scar consistent with a propeller blade strike was found near the impact crater, where one blade was located. The other propeller blade was recovered about 100 ft from the main wreckage. Both blades showed light rotational chordwise scratches from dirt, and minimal damage to the blade leading edges. There was no evidence of fire on any portion of the airplane. There was evidence of fuel blight in the field and a witness reported smelling fuel.

    The engine was hoisted from the remaining engine mount, and the rocker box covers removed to facilitate examination. The crankshaft rotated when the propeller was rotated by hand, and continuity of the crankshaft to the camshaft was confirmed. Thumb compression was established on cylinder Nos. 1, 2, and 4, and on cylinder No. 3 after the impact-damaged exhaust valve pushrod was removed. Borescope inspection of all cylinders revealed no anomalies. The carburetor, with throttle and mixture control cables attached, was impact separated from the bottom of the sump housing and next to the engine at the accident location. Liquid consistent with fuel was noted inside the carburetor bowl and in the fuel pump. Both magnetos had impact damage to the mounting flanges. The left magneto was not capable of producing spark due to the capacitor being impact separated from the unit. The unit was opened for further examination and the points opened and closed as expected when the shaft was rotated. The right magneto produced spark at all four leads when rotated with a drill. The oil filter element appeared clean. Examination of the engine revealed no pre-impact anomalies that would have prevented normal operation.

    Examination of the airframe revealed the wing spars remained attached to the fuselage structure and both wing fuel tanks were breached. All flight control cables and tubes were connected at their associated cockpit surfaces. Aileron continuity was established from the cockpit control stick to the aileron control surfaces. Left rudder continuity was established from the cockpit rudder pedals to the rudder control horn; however, right rudder continuity could only be established from the cockpit rudder pedals to the cable end loop, which was not attached to the clevis at the rudder control horn. The clevis was opened and hanging from the control horn, and the clevis pin was located nearby. Examination of the elevator trim cables revealed that both cables were continuous from their attachment points at the cockpit trim control lever, through broom-strawed fractures consistent with tensile overload above the rear pilot seat, to each control surface; however, the right elevator trim tab had separated from the elevator at the two hinged attachment points.

    The pilot seats remained attached to their rails, and the seatbelts remained attached to their mounts. The rear pilot’s seat was equipped with the lap belt which was cut to assist in the recovery of the pilot-rated passenger. The forward pilot’s seat was equipped with a lap belt and shoulder harnesses, which were intact, unlatched, and undamaged.

    The airplane was retained for further examination.​

    Aviation Safety Network Page
    On October 29, 2022, about 1452 eastern daylight time, an experimental amateur-built Bearhawk Patrol airplane, N964RS, was substantially damaged when it was involved in an accident near H...


    NTSB Final Report
    https://data.ntsb.gov/carol-repgen/a...ort/106223/pdf
    Last edited by Nev; 04-13-2024, 02:31 AM.
    Nev Bailey
    Christchurch, NZ

    BearhawkBlog.com - Safety & Maintenance Notes
    YouTube - Build and flying channel
    Builders Log - We build planes

  • #2
    The NTSB Final report is now issued HERE.
    Last edited by Nev; 04-12-2024, 03:30 AM.
    Nev Bailey
    Christchurch, NZ

    BearhawkBlog.com - Safety & Maintenance Notes
    YouTube - Build and flying channel
    Builders Log - We build planes

    Comment


    • #3
      Thanks Nev for the follow up. It is interesting that seat-belts and their use seem to be an important factor in both this and the Kalispell accidents.
      Last edited by rkennell; 04-12-2024, 07:17 AM.
      Roger
      QB Companion C-9
      N51RK

      Comment


      • #4
        Yes, that is interesting. There are good reasons to keep everyone buckled firmly in place.

        Comment


        • #5
          Originally posted by rkennell View Post
          Thanks Nev for the follow up. It is interesting that seat-belts and their use seem to be an important factor in both this and the Kalispell accidents.
          The abrupt pitch down, then up, seems to be a similar pattern too, the NTSB said the ADSB data showed an initial loss of 400 ft in 2 seconds (equates to 12,000 ft/min).

          Due to the significant damage it's very difficult to tell if any was pre-existing, but one picture drew my attention - the bent lower longeron is very similar to what we saw on 2 NZ BH's (More info in the thread HERE), caused by turning tightly while taxying over uneven ground with the tailwheel close to 90 °.

          84747647-2E7D-4C05-B66B-0BEFC252AFB9.jpg
          Last edited by Nev; 04-12-2024, 05:43 PM.
          Nev Bailey
          Christchurch, NZ

          BearhawkBlog.com - Safety & Maintenance Notes
          YouTube - Build and flying channel
          Builders Log - We build planes

          Comment


          • #6
            I don't know how to respond. I am concerned that the NTSB's probable cause is wrong. NEV, Thank you for sharing this data on the engineering change adding a gusset at the tail. Do we know if the tail had the gusset, and if it was damaged could it cause a control jam of the elevator?
            Brooks Cone
            Southeast Michigan
            Patrol #303, Kit build

            Comment


            • #7
              It appears the gusset mod is not included in the image above. Hard to tell from the photograph but it appears the lower part of the tail post is missing.

              If the yaw symptom that had been investigated was caused by snagging of a cable or swage, or binding of a hinge or something else, it may not have been possible to determine due to accident damage.

              Comment


              • #8
                One thing that I hadn't comprehended until today was how anyone could exit the aircraft through the skylight. Certainly in a Bearhawk 4-place, there are several structural braces that would make this very unlikely. However I visited Graham Johnson today (he took me for a flight in his gorgeous Patrol). The Patrol has a different bracing structure overhead the front seat, and it would allow a normal adult to fit between the bracing just aft of the wing-spar carry-through. So previously, I was thinking that a violent pitch down would be required, but I can now see that only enough pitch down to break through the skylight would be required if the seatbelt was already undone. In our Bearhawks the negative G design limit is around -1.67, so the difference between enough to float someone up out of their seat, and enough to exceed the negative structural limit, is not a lot different.
                Nev Bailey
                Christchurch, NZ

                BearhawkBlog.com - Safety & Maintenance Notes
                YouTube - Build and flying channel
                Builders Log - We build planes

                Comment


                • #9
                  My Patrol was covered prior to the safety notice coming out so I did not install the gusset, figuring it was not mandatory. Bob validates that its Non-mandatory, so I will mitigate the risk using caution and prudence during taxi operations, write a limitation on tight turns in rough ground until the gusset gets installed. Debate in my mind is ongoing though.

                  I have some thoughts about mitigating risk also through attention to detail on a preflight inspection of the lower longerons and tail post area. Anyone have any better mitigation ideas?
                  Brooks Cone
                  Southeast Michigan
                  Patrol #303, Kit build

                  Comment


                  • #10
                    Originally posted by Bcone1381 View Post
                    My Patrol was covered prior to the safety notice coming out so I did not install the gusset, figuring it was not mandatory. Bob validates that its Non-mandatory, so I will mitigate the risk using caution and prudence during taxi operations, write a limitation on tight turns in rough ground until the gusset gets installed. Debate in my mind is ongoing though.

                    I have some thoughts about mitigating risk also through attention to detail on a preflight inspection of the lower longerons and tail post area. Anyone have any better mitigation ideas?
                    My mitigation plan is the same as yours Brooks. Knowing that the aft area is vulnerable in that specific situation of tight turns on rough ground and therefore turning slowly or getting out and pushing, and getting an eye along the longerons during preflight. There's a long history of damage in the aft area of tailwheel aircraft, not limited to the BH, but certainly when operating off-airport the risk increases. Long grass can easily hide obstacles. At very low landing speeds the tailwheel can easily touch down before the mains. I'm not sure how much risk, (if any) this adds, except that the forces should generally be aligned in the way the structure is designed to accept them.

                    Battson's excellent post HERE documents tailpost damage associated with the A model leaf spring after 870 hours, and he discusses the forces involved in both tailwheel suspension types HERE. The B model stinger may in some ways have mitigated the tail post risk, but appears to have transferred more of it to the longerons. I'm not sure if we can remove the risk altogether, but awareness of it should certainly help.
                    Nev Bailey
                    Christchurch, NZ

                    BearhawkBlog.com - Safety & Maintenance Notes
                    YouTube - Build and flying channel
                    Builders Log - We build planes

                    Comment


                    • #11
                      Brooks, did you ask Bob if he saw any possible connection between longerons and either of those two crashes? I didn't ask him about it yet.

                      Comment

                      Working...
                      X