Effingham, SC, USA
N11JK
BEECH V35B
The pilot reported that he was conducting a cross-country instrument flight rules flight, and, during the cruise portion of the flight, he intermittently encountered areas of instrument meteorological conditions (IMC). About 1 hour 50 minutes into the flight, an air traffic controller advised the pilot of an area of moderate-to-extreme precipitation 20 miles ahead, extending along the intended route of flight for 100 miles. Eight minutes later, the pilot contacted an air traffic controller and requested a descent from 12,000 to 10,000 ft mean sea level (msl) "for weather," but he did not receive a reply to the request, and the airplane continued on-course. After an additional 8 minutes, the pilot reattempted to contact a controller but was interrupted by another pilot, and he again received no response. The pilot attempted to contact a controller a third time and requested a turn to get out of the weather. This time a controller responded and advised the pilot to turn left, but, just as the pilot initiated the left turn, the airplane encountered an area of severe turbulence. The pilot reported that, while in the turbulence, the airplane encountered an updraft that put the airplane in a 4,000 ft per minute climb and that the airspeed reached 253 knots, which exceeded the airplane's never-exceed airspeed. The airplane then encountered a downdraft, which caused the airplane to lose 3,000 ft of altitude, and the primary flight display simultaneously "went black." When the display returned, it showed a message advising the pilot to "level the wings" while the attitude and heading reference system realigned. The pilot subsequently used the standby instrumentation to control the airplane while he initiated an emergency descent. The airplane exited the turbulence and IMC about 4,000 ft msl, and, shortly thereafter, the propeller separated from the engine. The pilot subsequently performed a forced landing to a cornfield, and the airplane sustained substantial damage to the fuselage and both wings. The pilot reported that he received a weather briefing before departing on the accident flight. According to audio recordings of the briefing, the weather briefer advised the pilot of the adverse conditions along his route of flight; the pilot replied, "Ok, I guess we'll deal with that when we get there, if we have to go around it or stop, that's fine." An air traffic controller again advised the pilot of the severe weather conditions at least 20 miles ahead of the encounter. It is unlikely that the pilot's initial unanswered request to descend to 10,000 ft msl would have prevented the weather encounter, and the pilot's second and third unsuccessful attempts to contact the controller occurred more than 15 minutes after he was first advised of the weather conditions. The pilot was clearly made aware that severe weather conditions existed along his route of flight, but he waited until too far into the flight to try and avoid them, which ultimately led to the flight's encountering the conditions that resulted in the in-flight loss of control. The air traffic controller complied with the Federal Aviation Administration's minimum requirement for "additional services" by providing the hazardous weather information to the pilot when he first checked in, but additional information by the controller would have been valuable. For example, as the flight continued tracking directly into known heavy-to-extreme precipitation that other aircraft were deviating around, the controller should have realized that the pilot was not taking action to avoid the weather and either suggested a deviation or at least updated him about the proximity of the hazardous weather that the airplane was rapidly approaching. Regardless, it was ultimately the pilot's responsibility to avoid the severe weather. The propeller hub was found detached from the airplane due to a failure caused by reverse bending fatigue of the mounting bolts connecting the hub assembly to the engine crankshaft mounting flange. All of the bolts exhibited features consistent with fatigue cracking in a circular direction along the same direction as the wear marks on the hub case aft face. The reverse bending failure of the hub mounting bolts was indicative of a loose connection between the hub and the crankshaft. None of the airplane's documented maintenance indicated that the propeller hub was removed during the year before the accident. The engine's fractured connecting rod exhibited a small thumbnail fatigue crack on one side. However, this small amount of fatigue likely occurred after the fatigue cracking had begun on the propeller bolts. Cracking in the propeller bolts would likely have created unbalanced loading in all of the connected components, including the crankshaft and connecting rod. Once the propeller separated from the crankshaft, the crankshaft absorbed the entire load exerted by the engine, and this increased loading likely in turn increased the friction at the contact surfaces beyond the capacity of the lubrication. Without sufficient lubricating capacity at the journals, the material would begin to heat excessively, creating local material deformation. The underlying reasons for the loose connection between the propeller hub and the crankshaft could not be determined, but it is likely that the extreme forces encountered during the flight's weather-induced upset and loss of control resulted in the ultimate failure of the connecting bolts.
HISTORY OF FLIGHTOn August 11, 2012, about 1310 eastern daylight time, a Beech V35B, N11JK, was substantially damaged during a forced landing near Effingham, South Carolina. The private pilot and the passenger were not injured. Instrument meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan was filed for the flight. The flight departed Manassas Regional Airport (HEF), Manassas, Virginia at 1052, and was destined for Flagler County Airport (XFL), Palm Coast, Florida. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. According to the pilot, prior to departing on the accident flight, he used a computer-based application to receive a textual weather briefing, and checked the weather conditions on the website of the National Oceanic and Atmospheric Administration (NOAA). He also contacted Lockheed Martin Flight Services, and after filing his IFR flight plan, briefly discussed weather conditions with the briefer. Review of the archived audio from the contact showed that the pilot was subsequently advised of two current convective SIGMETs, in the vicinities of central South Carolina and northern Florida. The pilot replied that he was aware of the SIGMETs. The briefer further advised that a line of weather was 130 miles west of the destination, and that the flight would likely arrive there before the adverse weather conditions did. The briefer then advised the pilot, "Probably the stuff in South Carolina could be the one that actually impacts your route of flight." The pilot responded, "Ok, I guess we'll deal with that when we get there, if we have to go around it or stop, that's fine." The briefer concluded the exchange, "…that's only about 50 miles off to the west." He then advised that the weather conditions at the destination airport, as well as locations further south, were generally favorable. The flight departed from HEF about 1052 and proceeded uneventfully until approaching the northern South Carolina border, about 1240. The flight was given a frequency change by air traffic control (ATC), and first attempted to contact Jacksonville Air Route Traffic Control Center (ZJX) at 1243; however, due to frequency congestion at the time, the controller did not hear the transmission. The pilot subsequently checked-in with ZJX, and reported that the airplane was level at 12,000 feet. The controller acknowledged and issued the local altimeter setting as well as an advisory for moderate to extreme precipitation 20 miles ahead extending to the south for 100 miles, which the pilot acknowledged. At 1244, the controller issued a broadcast to all aircraft that stated AIRMET "Tango" for Tennessee, Louisiana, Mississippi, Alabama, and coastal waters was available on HIWAS , flight watch, or flight service frequencies. At 1252, the pilot requested to descend to 10,000 feet, "for weather". This transmission was not acknowledged by the controller and at 1300:12 the pilot re-attempted contact but was interrupted by another aircraft calling, and again received no response. At 1300:32 the accident pilot called again and requested a turn to get out of the weather. The controller instructed the pilot to deviate left and then proceed direct to CHS VOR, Charleston, South Carolina, when able. At 1302:49, the controller informed the pilot that he thought he would be in the weather for another minute, and the weather would then be clear to Charleston. At 1302:56, the pilot reported that he had encountered heavy turbulence and was unable to maintain altitude. The controller acknowledged, informed the pilot that he was almost out of the weather, and instructed him to continue flying his present heading. At 1303:56, the accident pilot attempted to contact ZJX and the transmission was cut off by another aircraft calling. The controller then instructed all aircraft to stand by, and instructed the accident pilot to retry his transmission. The accident pilot again reported that he was losing altitude and had also "lost" his attitude and heading reference system (AHRS). The controller then asked the pilot if he could level the airplane and instructed him to fly heading 090. At 1304:56 the controller asked the pilot to verify his altitude, and the pilot responded that he was at 4,000 feet and was underneath the weather. The controller then asked the pilot if he was stabilized and level at 4,000 feet. At 1305:18 the pilot stated he was at 3,000 feet and then his transmission was cut off. At 1305:29, the controller instructed the pilot to contact Florence Regional Airport (FLO), Florence, South Carolina, approach control and at 1305:35 the pilot responded stating that the airplane had lost engine power. The controller instructed the pilot to make a left turn to heading 360 toward Florence, and the pilot acknowledged. At 1306:03 the controller informed the pilot that FLO was 15 miles from the airplane's position, on an approximate heading of 20 degrees. At 1306:48 the controller informed the pilot about the available landing runways at FLO, along with the current weather conditions. At 1307:51 the controller asked the pilot if he could change radio frequencies or if he would rather remain with him, and the accident pilot responded stating "…let me stay with you, I'm a little busy right now". At 1308:08 the controller cleared the pilot to land on any runway at FLO. At 1308:51 the pilot stated that he did not think he was going to make the airport, could not see it, and was going to have to land in a field. At 1309:05 the accident pilot stated "Jacksonville, one one juliet kilo can't make the airport" which was the last recorded transmission received from the pilot. At 1312:05 another airplane relayed to ZJX that they were in contact with the accident pilot, and that he was on the ground and they were okay, but that the engine was on fire and they needed fire and rescue to respond. PERSONNEL INFORMATIONThe pilot held a private pilot certificate with ratings for airplane single engine and instrument airplane. His most recent FAA third-class medical certificate was issued on September 28, 2010. He reported that at the time of the accident he had accumulated about 800 total hours of flight experience. Additionally, he reported that he had received about 40 hours of dual flight instruction in the accident airplane as required by his insurance carrier, and had since accumulated 150 total hours of flight experience in the airplane. AIRCRAFT INFORMATIONAccording to FAA airworthiness records, the airplane was manufactured in 1973. It was originally equipped with a Continental Motors IO-520-BA engine. In May 2001 and May 2009 the engine was disassembled, cleaned, and inspected following two separate propeller strike/sudden stoppage incidents. Following the propeller strike event in 2009, an MT Propeller MTV-9-D/210-58, three-blade composite propeller was installed onto the engine. In July 2011, the engine was removed and modified with the installation of a turbo-normalizing system in accordance with Western Skyways STC SA8676SW. Maintenance log entries documenting the modification of the engine also noted the removal and reinstallation of the propeller, and no subsequent entries in any of the maintenance logs documented additional removal or reinstallation of the propeller. An annual inspection of the airframe, engine, and propeller was completed in December 2011, at which time the airframe and engine had accumulated 2,847 total hours of operation, 908 hours of which were accumulated since the engine's last major overhaul in 1987. The airplane's most recent maintenance log entry detailed an engine oil and oil filter change on March 15, 2012, at an airframe total time of 2,878 flight hours. According to FAA aircraft registration records, the pilot purchased the accident airplane in September 2008. Review of maintenance records showed that in October 2008, the airplane's avionics were reconfigured to include the installation of a Garmin GNS 430W and a Garmin MX-20 MFD at an airframe total time of 2,613 hours. In June 2009, an Aspen Pro 1000 EFIS and a Garmin GDL-90 UAT (ADSB) Data Link Sensor was installed, at an airframe total time of 2,636 hours. In June 2010, the Aspen Pro 1000 EFIS and the Garmin GDL-90 were removed and a Garmin G-500 system was installed, at an airframe total time of 2,701 hours. In September 2010, a Garmin GDL-69 (satellite) Weather Data Link system was installed, at an airframe total time of 2,723 hours. In June 2011, a Garmin GTN-750 navigation/communication/GPS receiver was installed, at an airframe total time of 2,783 hours. METEOROLOGICAL INFORMATIONThe National Weather Service (NWS) Surface Analysis Chart for 1400 depicted a stationary front stretched northeastward from central Georgia up the East Coast. A cold front stretched southwestward from central Georgia into Alabama. Several outflow boundaries were located across South Carolina and Georgia; these outflow boundaries, along with the frontal boundaries, acted as lifting mechanisms to help produce clouds and precipitation. The station models around the accident site depicted a southwest to south wind between 5 and 20 knots, partly cloudy skies, and thunderstorms. The low-level environment surrounding the accident site was warm and moist, conducive to the creation of moderately unstable conditions which, when combined with the lifting mechanisms, resulted in clouds, rain showers, and strong thunderstorms. The Area Forecast issued at 0718 forecasted a broken ceiling at 1,000 feet msl with the cloud tops at 10,000 feet msl. The ceilings were forecast to rise to 3,000 feet msl between 1100 and 1300. Scattered light rain showers and thunderstorms were forecast across central South Carolina with tops to FL380. Florence Regional Airport was the closest official weather station to the accident site, and had an Automated Surface Observing System whose reports were supplemented by the air traffic control tower. FLO was located 4 miles north of the accident site, at an elevation of 147 feet. The following observations were taken and disseminated during the times surrounding the accident: FLO weather at 1253 included wind from 220 degrees at 6 knots, 10 miles visibility, scattered clouds at 3,400 feet agl, scattered clouds at 11,000 feet agl, temperature of 29 degrees C, dew point temperature of 23 degrees C, and an altimeter setting of 29.92 inches of mercury. Remarks: automated station with a precipitation discriminator, sea-level pressure 1012.9 hPa, temperature 29.4 degrees C, dew point temperature 22.8 degrees C. FLO weather at 1330 included wind from 220 degrees at 8 knots with gusts to 25 knots, 1 and three-quarter miles visibility, heavy rain and mist, few clouds at 3,300 feet agl, a broken ceiling at 4,900 feet agl, temperature of 22 degrees C, dew point temperature of 20 degrees C, and an altimeter setting of 29.97 inches of mercury. Remarks: automated station with a precipitation discriminator, peak wind from 260 degrees at 33 knots at 1314, rain began 1314, one-hourly precipitation of 0.08 inches. FLO weather at 1333 included wind from 250 degrees at 4 knots, 2 miles visibility, a thunderstorm and rain, few clouds at 3,400 feet agl, a broken ceiling at 4,900 feet agl, broken skies at 11,000 feet agl, temperature of 22 degrees C, dew point temperature of 20 degrees C, and an altimeter setting of 29.96 inches of mercury. Remarks: automated station with a precipitation discriminator, peak wind from 260 degrees at 33 knots at 1314, rain began 1314, thunderstorm began at 1333, one-hourly precipitation of 0.09 inches. The observations from the airports surrounding the accident site at the time of the accident indicated thunderstorms and lightning prevailed. Surface winds at the airports were variable and gusty around the accident time, likely due to the strong winds initiated by the area of thunderstorms. A North American Mesoscale (NAM) model sounding was generated for the accident site for 1400. The model sounding depicted a moist, conditionally-unstable vertical environment and a freezing level of 14,612 feet. The environment would generally have been supportive of cloud formation, rain showers, and thunderstorms. The sounding identified the possibility of clouds between the surface and 24,000 feet, and indicated the possible presence of clear-air turbulence and low-level wind shear from the surface through 10,000 feet. Visible data from the Geostationary Operational Environmental Satellite number 13 from 1302 and 1315 revealed cumuliform clouds at the accident site with the line of cumuliform clouds moving eastward with time. Inspection of the infrared imagery indicated cooler (higher) clouds tops at and just to the west of the accident site at the accident time. Based on the brightness temperatures above the accident site and the vertical temperature profile provided by the 1400 NAM sounding, the approximate cloud-top heights over the accident site were 35,000 feet at 1315. The radar summary image from 1315 depicted reflectivity in the vicinity of the accident site with 45 to 55 dBZ values, and indicated the presence of very strong to extreme echoes around the accident time. The closest NWS Weather Surveillance Radar (WSR-88D) was located near Wilmington, North Carolina (LTX), approximately 65 miles east of the accident site at an elevation of 64 feet. The reflectivity image for the 1.3-degree elevation scan initiated at 1301, and the base reflectivity image for the 0.5-degree elevation scans initiated at 1305 and 1310 showed that 50 to 65 dBZ values occurred along the airplane's ATC radar-recorded flight track, indicating that the airplane likely encountered very strong to extreme precipitation. Lightning flash data from 1245 to 1305 was plotted and revealed that lightning encompassed the airplane's flight track, with over 1,800 individual lightning flashes occurring during that period. Given the base reflectivity and lightning data, the airplane likely encountered very strong to extreme precipitation. Figure 1 - LTX WSR-88D reflectivity for the 1.3 degrees elevation scan initiated at 1301 with lightning flash data from 1245 to 1305 A 3-dimensional view of the LTX WSR-88D base reflectivity for the elevation scans initiated at 1301 and 1305 showed the accident flight encountering greater than 50 dBZ values at both time points. Much like the base reflectivity discussed previously, the flight likely encountered intense to extreme precipitation while flying through a line of thunderstorms. Figure 2 - 3-dimensional LTX base reflectivity from the scan initiated at 1301 and the ATC Flight Track SIGMETs 26E and 23E were valid at the accident time along the accident route of flight. These SIGMETs advised of a line of thunderstorms and an area of thunderstorms moving from 250 degrees at 25 knots with tops above FL450. The thunderstorm line was 35 miles wide. A special weather statement was issued by the NWS in Wilmington, North Carolina, at 1229 for the line of strong thunderstorms the accident aircraft would encounter. These thunderstorms were moving northeastward at 40 mph with pea-sized hail and gusty winds of 40 to 50 mph possible at the surface. AIRPORT INFORMATIONAccording to FAA airworthiness records, the airplane was manufactured in 1973. It was originally equipped with a Continental Motors IO-520-BA engine. In May 2001 and May 2009 the engine was disassembled, cleaned, and inspected following two separate propeller strike/sudden stoppage incidents. Following the propeller strike event in 2009, an MT Propeller MTV-9-D/210-58, three-blade composite propeller was installed onto the engine. In July 2011, the engine was removed and modified with the installation of a turbo-normalizing system in accordance with Western Skyways STC SA8676SW. Maintenance log entries documenting the modification of the engine also noted the removal and reinstallation of the propeller, and no subsequent entries in any of the maintenance logs documented additional removal or reinstallation of the propeller. An annual inspection of the airframe, engine, and propeller was completed in December 2011, at which time the airframe and engine had accumulated 2,847 total hours of operation, 908 hours of which were accumulated
The pilot's failure to avoid an encounter with known adverse weather conditions, which resulted in an in-flight upset, temporary loss of control, and loading of the airframe, engine, and propeller that led to the in-flight separation of the propeller and the subsequent forced landing. The root cause for the separation of the propeller could not be determined based on the available information.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
