N6BSCessna 310 · 1956

On November 4, 2012, approximately 1800 central standard time, N6BS, a twin-engine Cessna 310 airplane, was substantially damaged when it collided with trees and terrain near Stotts City, Missouri. The commercial pilot and the pilot rated passenger were fatally injured. The airplane was registered to and operated by the pilot rated passenger. No flight plan was filed for the flight that originated from the Monett Regional Airport (HFJ), Monett, Missouri, about 1735, and destined for a private airstrip in Miller, Missouri. Night visual meteorological conditions prevailed for the repositioning flight conducted under 14 Code of Federal Regulations Part 91.

According to a pilot rated witness, the airplane's right engine was recently overhauled and the accident flight was the first flight after the new engine was installed. He said the pilots had originally planned to fly to Miller on November 2nd, but had to postpone the flight because the left main landing gear brake was "soft" during the engine run-up. In addition to the left main landing gear brake problem, the nose landing gear strut was also flat.

According to the mechanic, who was hired to overhaul the engine, the pilot rated passenger asked him if he would fix the nose gear strut. The mechanic told him it would take at least a day to complete the repair. Since the owner planned to fly the airplane to Ohio later that week for a corrosion inspection; he told the mechanic he would have the gear fixed then. In the meantime, he would fly with the landing gear extended because he was concerned the gear would get stuck in the nose well. As a temporary fix, the mechanic used shop-air provided by the Monett Airport manager to inflate the nose gear strut.

The witness stated that the flight was re-scheduled for November 4th and he met both pilots at the Monett airport around 1700. During the preflight inspection, the pilots noted the nose gear strut was flat again and there was another discussion about keeping the gear extended for the flight. The two pilots boarded the accident airplane, started the engines, and taxied toward the runway. The airplane stopped on the taxiway and the engines were run-up three or four times. He said the pilots then taxied back to the hangar and shut the engines down. The pilot exited the airplane and said the right propeller was not "feathering" and needed to be fixed. The passenger called the same mechanic and asked him if he could look at the problem. The mechanic arrived 30-40 minutes later and opened the right inboard cowling on the right engine. About five minutes later, the mechanic said they were, "Good to go."

According to the mechanic, the pilot rated passenger called him at 1648 and told him that the right propeller control lever was not moving smoothly through its full range of travel. There was no mention that the propeller was not feathering. The mechanic said he was surprised that they were planning to do an engine flight test at night. About 30-40 minutes later he arrived at the Monett airport and opened up the right inboard cowling for the right engine. The mechanic asked one of the pilots to move the propeller control lever in the cockpit through its full range of travel. The mechanic said the arm on the propeller governor moved smoothly from stop to stop as the lever was moved. He told one of the pilots to adjust the friction lock for the lever, which eased the tightness of the lever. He also noticed the nose gear strut was flat again.

The witness said he heard the pilot and passenger discussing if they should postpone the flight because it was getting dark. They were originally going to make a few circuits around the traffic pattern before they flew to Miller. However, since they were delayed they agreed to just fly to Miller.

The pilots got back in the accident airplane; the pilot passenger sat in the front left seat and the pilot sat in the front right seat. Both engines started normally and the airplane taxied toward the runway where another long engine run-up on the taxiway was conducted, which included cycling the propeller several times. The witness also noted that only the airplane's beacon lights were turned on.

The mechanic also observed the airplane before it departed and provided a similar account of the engine run-up. He also confirmed that only the beacon lights were turned on.

After the accident airplane departed runway 18, the witness departed in another airplane and followed them to Miller, which was 24 miles north of Monett. The witness planned to fly the pilot and pilot rated passenger back to Monett after they dropped off the accident airplane.

The mechanic said that he was surprised when he saw the airplane heading north toward Miller because he thought they were going to stay in the traffic pattern to test the engine. He then called his assistant, who lived at the private airstrip in Miller, and told him that the accident airplane was headed that way.

In an interview, the assistant said he received a call from the mechanic at 1738. He was surprised that anyone would attempt to land on an unlighted grass airstrip at night. The assistant said that by the time he and his girlfriend walked over to the runway, he could see the airplane approaching from the west. Only the airplane's beacon lights were turned on and he could not tell if the landing gear were extended because it was too dark. The airplane was approximately 500 to-800 feet above the ground and in a level flying attitude. The assistant said both engines sounded normal and there was "nothing indicating any distress." The airplane then made a smooth right turn toward the south and maintained a constant altitude. As the airplane turned south, the assistant said he got a call from the owner of the airstrip asking if he would bring a fire extinguisher out to the airplane when it landed. The assistant said he grabbed a nearby extinguisher, but the airplane never returned.

The witness said that after he departed Monett airport, he established communication with the other pilots via a common air-to-air traffic frequency and made visual contact with the accident airplane. While en route, noted that the accident airplane was not on course for the private airstrip. The pilot rated passenger asked if they were heading in the right direction and the witness said they needed to correct 20-30 degrees back to the left. Shortly after, the pilot rated passenger said that "fuel or oil" was coming out of the right engine. He asked the witness to arrange for a fire extinguisher to be available when they landed, which he did. A few minutes later, the pilot rated passenger asked the witness where the private airstrip was located, and the witness told him they were "right on top of it." The pilot rated passenger then said they were losing oil pressure and were returning to Monett, followed by, "We shut the engine down." The witness responded, "Ok, I'll follow you." At this time, the witness said the accident airplane was turning from crosswind to downwind approximately 800-900 feet above the ground over the private airstrip. The witness said he then flew up along the right side of the accident airplane and noted that there was no smoke or fire coming from the engine. The witness then trailed back and to the right. He could not recall if the landing gear were extended, but did recall that the light on the nose gear was turned on.

According to the witness, when the accident airplane was approximately 1 mile south of the private airstrip, the passenger announced, "110 knots" over the radio frequency. About 30 seconds later, the passenger said they were having trouble gaining altitude followed by they were not able to maintain altitude. The passenger then asked the witness for a vector to Mount Vernon Airport. The witness responded that it was 127 degrees and 4 miles, and he turned the runway lights on for them. The passenger again informed the witness that they were not able to maintain altitude. The witness said he could see the airplane losing altitude and advised them that Interstate 44 was one mile ahead. The pilot then announced they were going to land on the interstate.

The witness said the accident airplane continued to lose altitude. The passenger then said, "Oh my God, I think we are going to crash." This statement was followed by, "We're going to crash." The witness said he saw the light on the accident airplane's nose gear illuminate the trees in front of them. Then the nose of the airplane pitched up, rolled slightly to the right, and then pitched forward, followed by flames and a fireball.

Several people on the ground also witnessed the accident. One witness stated that he was at his home located about 1 mile northeast of the accident site when he first heard the airplane. He ran out on to his porch and established visual contact with the airplane. The airplane was descending toward the south, and the wings were "rocking" side to side. He said a bright "spotlight" was turned on at the bottom of the airplane. The witness, who was a diesel engine mechanic, said it sounded like only one of the airplane's engines was running, but he could not confirm which engine. He described the sound of the engine as revving up and down as if the pilot was "jockey-ing" the throttle. There was no smoke or fire trailing behind the airplane. The airplane then "dropped down" toward trees and the "throttle went wide open." Finally, the airplane "leaned off to the side" and he heard the sound of the airplane impacting the trees followed by two explosions. The witness saw a large cloud of black smoke and immediately went to the accident site.

A second ground witness stated that he was walking out of the woods after hunting about 6-7 miles north of the accident site when he saw two airplanes flying south and were about 100 yards apart from each other. He said there was no smoke or fire trailing either airplane and both had their lights turned on. The witness said the "airplane on the right" had a "very bright spotlight" turned on. Both airplanes were 500 feet or higher above the ground and he did not hear the engines. The witness said he could not see any landing gear because it was "too dark outside."

Another ground witness stated he was driving in his truck about ¾-mile north of the accident site when he first heard and saw the airplane. He said it flew directly over-head and was heading due south approximately 600 feet above the ground. The witness said it was dusk, around 1800, but still light outside. He said the airplane was descending in level flight and "the engine" was revving up and down. There was no smoke or fire trailing the airplane. He did not see any lights on the airplane, and thought the landing gear was extended. He said the airplane disappeared out of his view behind a house and made a "hard right bank." The witness did not see the airplane impact terrain but did see a large fireball moments later.

The pilot held a commercial pilot certificate for airplane single and multi-engine land, and instrument airplane. He was also a certified flight instructor for airplane single and multi-engine land, and instrument airplane. In addition, he held an airframe and power plant (A&P) certificate. A review of his logbook revealed that as of October 6, 2012, he had a total of 3,299 flight hours; 411 hours in multi-engine airplanes, of which, 102 hours were in a Cessna 310.

The pilot rated passenger held a private pilot certificate for airplane single-engine land, and instrument airplane. A review of his logbook revealed that as of September 28, 2012, he had a total of 1,621.8 hours; of which, all 10.6 hours of multi-engine time were in the accident airplane.

A review of the airplane's maintenance logbooks revealed the accident airplane did not have a current annual inspection as required by Federal Aviation Regulation (FAR) 91.409. The last annual inspection was completed on August 10, 2010, at a total time of 4,549.7 hours.

In September 2011, the airplane's previous owner hired a mechanic based in Arkansas to perform an annual inspection. According to the mechanic, the airplane was unairworthy because the nose-jack point had collapsed into the belly of the airplane and "a lot" of corrosion was found in the forward cabin bulkhead. Two Federal Aviation Administration (FAA) inspectors from the Little Rock Flight Standards District Office also examined the airplane and concurred that the airplane was unairworthy. The mechanic entered the unairworthy items in the aircraft logbook and made an endorsement that the airplane was "safe" to be ferried back to Missouri with the "gear down only." The FAA issued the owner a "Special Flight Permit" for this flight on November 10, 2011.

The passenger purchased the airplane in January 2012 and according to FAA records, was registered on April 2, 2012. At some point, the airplane was flown to Miami, Oklahoma, for an annual inspection. According to the aircraft logbook, on February 12, 2012, the mechanic that was hired to perform the inspection wrote, "No corrosion of significant airworthy found," but did observe "buckling caused by improper jacking not airworthy condition." According to the FAA, there were no records that a ferry permit was issued for the flight to or from Miami, Oklahoma. A review of both pilot's logbooks revealed the airplane was flown a total of 8 times after the last "Special Flight Permit" was issued in 2011.

The mechanic, who was hired to overhaul the engine, said he talked to the pilot on November 2nd, before the first planned test flight regarding the work he had performed on the engine. The mechanic said he had the right engine logbook, yellow tags and the engine data plate spread out on the horizontal stabilizer for the pilot to review, since he was also a mechanic. However, he said the pilot never looked at the logbook. He told the pilot that he had not "signed off" on the overhaul and was waiting for some older components to be replaced in addition to the flight test. At that time, he planned to sign off the work as a repair only. The mechanic said that after they talked, he gave the pilot the logbook along with the yellow tags and engine data plate because the pilot said the pilot rated passenger, who owned the airplane, wanted to review them. After the accident, the mechanic turned over the airplane's remaining maintenance logbooks that he had in his possession. The right engine logbook was never located.

At 1753, the automated weather report at Joplin Regional Airport (JLN), Joplin, Missouri, about 24 miles west of the accident site, was reported as wind from 120 degrees at 3 knots, clear skies, temperature 13 degrees Celsius, dewpoint 3 degrees Celsius, and a barometric pressure setting of 30.08 inches of mercury.

A review of the airplane's maintenance logbooks revealed the accident airplane did not have a current annual inspection as required by Federal Aviation Regulation (FAR) 91.409. The last annual inspection was completed on August 10, 2010, at a total time of 4,549.7 hours.

In September 2011, the airplane's previous owner hired a mechanic based in Arkansas to perform an annual inspection. According to the mechanic, the airplane was unairworthy because the nose-jack point had collapsed into the belly of the airplane and "a lot" of corrosion was found in the forward cabin bulkhead. Two Federal Aviation Administration (FAA) inspectors from the Little Rock Flight Standards District Office also examined the airplane and concurred that the airplane was unairworthy. The mechanic entered the unairworthy items in the aircraft logbook and made an endorsement that the airplane was "safe" to be ferried back to Missouri with the "gear down only." The FAA issued the owner a "Special Flight Permit" for this flight on November 10, 2011.

The passenger purchased the airplane in January 2012 and according to FAA records, was registered on April 2, 2012. At some point, the airplane was flown to Miami, Oklahoma, for an annual inspection. According to the aircraft logbook, on February 12, 2012, the mechanic that was hired to perform the inspection wrote, "No corrosion of significant airworthy found," but did observe "buckling caused by improper jacking not airworthy condition." According to the FAA, there were no records that a ferry permit was issued for the flight to or from Miami, Oklahoma. A review of both pilot's logbooks revealed the airplane was flown a total of 8 times after the last "Special Flight Permit" was issued in 2011.

The mechanic, who was hired to overhaul the engine, said he talked to the pilot on November 2nd, before the first planned test flight regarding the work he had performed on the engine. The mechanic said he had the right engine logbook, yellow tags and the engine data plate spread out on the horizontal stabilizer for the pilot to review, since he was also a mechanic. However, he said the pilot never looked at the logbook. He told the pilot that he had not "signed off" on the overhaul and was waiting for some older components to be replaced in addition to the flight test. At that time, he planned to sign off the work as a repair only. The mechanic said that after they talked, he gave the pilot the logbook along with the yellow tags and engine data plate because the pilot said the pilot rated passenger, who owned the airplane, wanted to review them. After the accident, the mechanic turned over the airplane's remaining maintenance logbooks that he had in his possession. The right engine logbook was never located.

The airplane collided with a stand of tall trees and traveled approximately 100 feet on a heading of 182 degrees before it came to rest on a pile of wooden planks and other debris. A post-impact fire consumed most of the cockpit, fuselage, and portions of both wings and the tail section. Impact marks on the trees were progressively lower along the wreckage path. Examination of the airplane revealed the flaps were in the retracted position and the landing gear were extended out of their respective wheel wells. Each of the wing mounted landing lights were found retracted. Both engines had separated from the airplane. The right propeller assembly had separated from the engine and was partially buried in the ground. The propeller blades were found in the feathered position. The left propeller assembly remained on the left engine. Both blades exhibited aft bending and leading edge damage.

Both engines were examined at Continental Motors Incorporated, Mobile, Alabama, on December 11-12, 2012, under the supervision of the National Transportation Safety Board Investigator-in-Charge (NTSB IIC).

External examination of the right engine revealed impact and thermal damage. The oil cooler; magnetos, vacuum pump, starter adapter, oil pump, and pressurized carburetor remained attached to the engine. The oil filter adapter was not properly attached to the engine and was not properly secured. There was also a thin coating of oil on the crankcase around the fitting. Approximately 2 quarts of dark oil were drained from the oil sump. There was a small breach in the sump from impact damage near the drain plug. The breach was on the seam of a weld point.

The adapter was not original to the engine and wasinstalled on the engine per supplemental type certificate (STC) (SE09356SC). Examination of the adapter revealed it was not properly safety-wired to the engine as per the installation instructions in the STC and was loose. The adapter was removed from the engine and disassembled. Two copper crush rings (gaskets) were found on the oil transfer cylinder. According to the STC, only one copper crush ring was to be used and a fiber leak-guard gasket was to be used at the base of the adapter. According to the STC holder, F&M Enterprises, Inc., if a fiber leak-guard gasket was not used, the oil adapter would leak due to an insufficient seal.

A test was conducted to determine what signatures would be made on a copper crush ring if it was installed at the base of the adapter using the suggested torque values per the STC. These signatures/dimensions were then compared to the ones left on the copper gasket originally found inside the adapter. A new copper crush ring was measured (.090-inches-wide) and placed on the right engine oil adapter. It was then torqued to the STC suggested torque value of 65 foot-pounds (ft/lbs) with a calibrated torque wrench. The ring was removed and measured (.052 inches-wide). There were also visible groves embedded in the copper material from the ridged grooves machined into the base of the adapter.

The original bottom copper crush ring found inside the right engine oil adapter measured approximately .074-inches wide. This ring and the test copper crush rings were examined under a microscope. The original ring did not exhibit the visible grooves observed on the test ring. Some groves were visible around 1/3 of the ring but were not as deep or pronounced as on the test ring.

According to the STC holder of the oil adapter, ridges were machined on the base of the adapter to help grab on to the fiber leak-guard gasket and create a better seal. When the fiber gasket gets oil soaked it expands and creates a better seal.

The test confirmed that the improperly installed original bottom copper crush ring did not exhibit the signatures or dimensions that would be created if it had been installed at the proper torque value.

Examination of the oil pump revealed that the tachometer drive adapter was sealed with silk thread. The threading observed on the oil pump was compared to the manufacturer's threading diagram presented in Service Information Letter (SIL99-2). The threading observed on the oil pump did not match, which could result in an oil leak.

Both magnetos were placed on a test bench and functioned normally.

Examination of the crankshaft, rods, bearings, camshaft, cranks case, pistons and cylinder assemblies revealed no mechanical anomalies.

External examination of the left engine revealed impact and extensive thermal damage. The oil cooler; magnetos, vacuum pump, starter adapter, oil pump, and pressurized carburetor remained attached to the engine. The oil filter adapter was still attached to the engine but the fitting was no tproperly secured and could be manually moved. No safety wire was noted on either the adapter or filter. Disassembly of the oil pump revealed that it too was not threaded properly. However, there were no mechanical malfunctions with the engine that would have precluded normal operation.

In a follow up interview with the mechanic, he said that he had removed the oil filter adapter from the right engine; disassembled the unit, replaced the gaskets with the copper gaskets, then reassembled the adapter and installed it back on the engine. He did not reference the STC instructions and did not use a torque wrench to tighten the adapter to the engine. He said he tightened it to "feel" what he thought was an industry standard of 60 ft/lbs. He said he also did not reference the STC installation instructions when applying the safety-wire. The mechanic also stated that he disassembled the oil pump and re-threaded the case. However, he did not reference the threading diagram presented in Continental Motors Incorporated (formerly Teledyne Continental Motors) Service Information Letter (SIL99-2).

A review of the 1956 Cessna 310 Owner's Manual revealed the single-engine climb-data chart only calculated single-engine climb rates with the flaps and gear retracted. The chart also assumed the inoperative propeller was feathered, and the wing was banked 5 degrees toward the operating engine, which would have to be at full throttle (2600 RPM) and leaned for best power. When the chart was interpolated for these and other conditions that existed at the time of the accident, the accident airplane would have had an approximate rate of climb of 566 feet per minute (ft/min). According to Cessna, the single-engine climb rate penalty if the gear was extended would have been about 400 ft/min. Based on this data, the accident airplane would have had a single-engine climb rate of about 166 ft/min at the time of the accident assuming the airplane was properly configured and the operating engine was producing full power.

An autopsy was conducted on the pilot by Southwest Missouri Forensics, Nixa, Missouri, on November 6, 2013. The cause of death was determined to be, "Exsanguination secondary to aortic laceration induced by blunt force trauma to the chest in an airplane crash."

Toxicological testing was conducted by the FAA Toxicology Accident Research Laboratory, Oklahoma City, Oklahoma. The results were positive for the following:

>34 (ug/ml, ug/g) Acetaminophen detected in urine

>0.013 (ug/ml. ug/g) Chlorpheniramine detected in blood (cavity)

>Chlorpheniramine detected in urine

>Salicylate detected in urine

Although Chlorpheniramine can be impairing, a review of the toxicology results by the NTSB Medical Officer found that the low level of Chlorpheniramine identified in post mortem cavity blood was unlikely to have contributed to the accident.

An autopsy was conducted on the pilot rated passenger by Southwest Missouri Forensics, Nixa, Missouri, on November 6, 2013. The cause of death was determined to be, "Cardiac arrhythmia secondary to myocardial hypoxia caused by hypoxemia due to the combined effects of multiple bilateral rib fractures (flail chest) and cardiac lacerations induced by blunt force trauma to the chest in an airplane crash."

Toxicological testing was conducted by the FAA Toxicology Accident Research Laboratory, Oklahoma City, Oklahoma. The results were negative for drugs and alcohol.