# NTSB CHI00LA238: Beech BE-A35, N8530A, Poplar Bluff, MO, July 31, 2000 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 30, 2000, 22:00 local (Jul 31, 2000, 03:00 UTC) - Place: Poplar Bluff, MO - Coordinates: 36.759025, -90.399368 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.7590&lon=-90.3994&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report October 2, 2001 - Report: Approved by Office Director - ADs cited in the narratives: [AD 98-13-02](https://openairdocs.org/ad/98-13-02) (OpenAirDocs) - NTSB case key (mKey): 49914 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI00LA238 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/49914/pdf - Page: https://openairdocs.org/ntsb/CHI00LA238 ## Probable cause the pilot exceeded the VNE speed restriction of 144 MPH. Factors included the ruddervator flutter and the out of balance ruddervators. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, descent - airspeed(vne) - exceeded, pilot in command (cause) - flight control,ruddervator - flutter (contributing factor) - flight control,ruddervator - out of balance (contributing factor) - Forced landing, emergency descent/landing ## Analysis The pilot reported the airplane was in a descent in smooth air when he heard a loud noise and the airplane began shaking. It stopped when he pulled back on the yoke and pulled the throttle back. He reported he saw the airspeed indicator needle passing below 144 mph on the airspeed indicator after the shaking stopped. The aircraft inspection revealed the aft fuselage and empennage received damage. All four corners of the F.S. 256.9 bulkhead were cracked. The left and right ruddervator static underbalance was checked. The left and right ruddervators were 20.25 inch pounds. The acceptable limits for ruddervator underbalance is 16.8 to 19.8 inch pounds. The airplane's maintenance records were reviewed. The left and right ruddervators were reskinned on October 23, 1996. The ruddervators were primed but not painted. The recorded static underbalance for both ruddervators was 19.5 inch pounds. There was no documentation of any maintenance performed on the ruddervators since they were reskinned. The Airworthiness Directive (AD) 98-13-02 that placed a speed restriction of 144 MPH indicated airspeed on the Models 35, A35, B35, and 35R airplanes had been complied with. The inspection of the airplane revealed it had the required placard and red line on the airspeed that notified the pilot the new VNE speed was 144 MPH. The VNE speed prior to the AD was 204 MPH. ## Factual narrative On July 30, 2000, at 2200 central daylight time, a Beech BE-A35, N8530A, was substantially damaged when it experienced tail flutter near Poplar Bluff, Missouri. The pilot reported the airplane was in a descent in smooth air. He reported there was a loud noise and the airplane began to shake. He reported the shaking stopped when he pulled back on the yoke and pulled the throttle back. He reported he saw the airspeed indicator needle passing below 144 mph after the shaking stopped. An uneventful landing was made to Poplar Bluff Municipal Airport (POF), Poplar Bluff, Missouri. The pilot and passenger were not injured. The 14 CFR Part 91 personal flight had departed Oshkosh, Wisconsin, at 1810 with POF as the final destination. Visual meteorological conditions prevailed, although, the pilot reported the flight had encountered rain showers in the area. No flight plan had been filed. The pilot reported he began his descent about 20 miles from the airport by reducing power. While he tuned in the airport advisory frequency he started getting a "control shake" in the control yoke. He reported, "I immediately pulled the nose up while simultaneously reducing the power which stopped the shaking. While applying corrective action I looked at the airspeed which was swinging thru the 144 red line. I slowed to gear speed extended the gear flew a straight in final and landed normally." The second pilot reported, "It felt like something hit the tail of the plane real hard and then there was a 2 second shudder. [The pilot] reduced the power and pulled up and I said what was that. He said I think its flutter. I said I think something hit us. We landed without incidence." A Federal Aviation Administration Airworthiness Inspector and a representative of the aircraft manufacturer examined the aircraft. The aircraft inspection revealed the left and right sides of the aft fuselage exhibited vertical creases and wrinkles at the Fuselage Station (F.S.) 256.9 bulkhead location. The upper fuselage skin exhibited creases and wrinkles running between the cutouts for the main spars of the stabilizers at the F.S. 256.9 bulkhead location. The lower aft fuselage skin exhibited bi-directional creases between the F.S. 233.5 bulkhead and the F.S. 207.0 bulkhead locations. All four corners of the F.S. 256.9 bulkhead were cracked. These cracks ran from the inside diameter of the bulkhead and extended outboard to the radius where the bulkhead attaches to the fuselage skin. The doubler was also cracked on the left rear side of he F.S. 256.9 bulkhead. The upper and lower skins of the left stabilizer exhibited a diagonal crease running form the outboard hinge location forward and inboard for about 5.5 inches. The ruddervator was primed but was not painted. The trim tab was installed correctly with the cambered side down and the hinge wire installed properly. The upper trim cable attached to the trim tab horn exhibited a radial movement of about 0.015 inches. After the ruddervator was removed from the empennage, it was noted that the middle and outboard hinge bushings exhibited an excessive amount of play. The lower skin of the right stabilizer exhibited a diagonal crease running from the outboard hinge location forward and inboard for approximately 1.0 inch. The upper skin of the right stabilizer exhibited a diagonal crease running from the outboard hinge location forward and inboard of about 3.0 inches. The trim tab was installed correctly with the cambered side down and the hinge wire installed properly. The lower trim cable attached to the trim tab horn exhibited a radial movement of about 0.025 inches and axial movement of 0.025 - 0.030 inches. After the ruddervator was removed from the empennage, it was noted the middle and outboard hinge bushings exhibited an excessive amount of play. Due to damage, the cable tensions were undeterminable. The ruddervator assemblies were removed and weighed with the trim tab and all mounting hardware included. The left assembly weighed 7.9 pounds and the right assembly weighed 8.0 pounds. The ruddervator static underbalance was checked. The left and right ruddervators were 20.25 inch pounds. The acceptable limits for ruddervator underbalance is 16.8 - 19.8 inch pounds. The tip weight assemblies were removed and weighed. The left weighed 2.8 pounds and the right was 2.6 pounds. The airplane's maintenance records were reviewed. The left and right ruddervators were reskinned on October 23, 1996. The ruddervators were primed but not painted. The recorded static underbalance for both ruddervators was 19.5 inch pounds. There was no documentation of any maintenance performed on the rudervators since they were reskinned. The Airworthiness Directive (AD) 98-13-02 that placed a VNE (Never Exceed) speed restriction of 144 MPH indicated airspeed on the Models 35, A35, B35, and 35R airplanes had been complied with. The inspection of the airplane revealed it had the required placard and red line on the airspeed that notified the pilot the new VNE speed was 144 MPH. The VNE speed prior to the AD was 204 MPH. Parties to the investigation were the FAA and Raytheon Aircraft Company. ## Aircraft - Registration: [N8530A](https://openairdocs.org/deregistered/N8530A-2013-05-14), registration cancelled 2013-05-14, S/N D-1952, built 1949 (OpenAirDocs) - Reported make and model: Beech BE-A35 - Registry model: [Beech A35](https://openairdocs.org/model/beech-a35) (registry code 1151504) (OpenAirDocs) - Registry engine: [Continental E225 series](https://openairdocs.org/engine/continental-e225-series) (registry code 17015, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: D1952 - Airframe hours: 4137 - Engines: Continental E225-8 225 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Richard W. Bowie - Airworthiness certificate: Standard, Normal - Last inspection: Annual, July 17, 2000, 10 hours before - Departed: OSH, OSHKOSH, WI - Destination: POF - Airport: POF, Poplar Bluff Municipal ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 41; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; seat: left; flight hours: 1,020 total, 102 in this make and model ## Weather - Conditions: Visual (VMC), Night/dark - Visibility: 5 statute miles - Lowest ceiling: 11,000 ft overcast - Temperature: 162 °F, dew point 158 °F - Altimeter: 30.00 inHg - Observed at: POF ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20000730008049A](https://openairdocs.org/incident/20000730008049A), Jul 30, 2000: Beech A35, Poplar Bluff, MO, No damage. (-23) While on approach into pof, pilot experienced several "pops" accompanied by control shuddering. Upon landing, pilot discovered damage to empennage… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.