Boulder City, NV, USA
N434M
BEECH A45
The pilot, who was also the mechanic for the airplane, had replaced all six cylinders on the engine during the airplane's annual inspection; he reported that, 3 days before the accident, the engine was operated and ran well. On the day of the accident, he was returning the airplane to its home base following a maintenance inspection on the wings. The pilot was near the end of the flight when he contacted approach control and requested priority handling because an engine chip light had illuminated. Shortly thereafter, the pilot stated that the engine had lost power on a cylinder, and he declared an emergency. When the airplane was at 9,500 ft mean sea level, the pilot said that he was going to attempt to land at a nearby airport (elevation 2,201 ft). Before switching to the airport's common traffic advisory frequency (CTAF), the pilot reported to the approach controller that the airplane was at 3,800 ft with the landing gear down and that the situation was under control. The pilot did not contact approach control again and did not broadcast over the CTAF. The airplane collided with terrain in a nose- low attitude about 1 mile west of the airport. Postaccident examination of the airframe revealed no evidence of mechanical anomalies that would have precluded normal operation. Postaccident examination of the engine revealed that the No. 6 cylinder had separated, and no nuts were located on its through bolts. Magnified examinations of the bolt threads found the thread profiles intact and only locally distorted, consistent with the nuts not being present during the No. 6 cylinder separation, which appeared to be the result of the incorrect assembly of the cylinder at the last cylinder change. Fretting damage on the mounting pad was observed, which indicates looseness and movement between the cylinder and the case that resulted from inadequate preload in the fasteners either through insufficient initial torque or loss of torque during operation. Considering the short time since cylinder installation, it is likely that the cylinder fasteners, or at least some of them, were not correctly torqued at installation.
HISTORY OF FLIGHTOn June 23, 2013, about 1443 Pacific daylight time, a Beech A45, N434M, collided with terrain during a forced landing near Boulder City, Nevada. Jet Test and Transport LLC was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The commercial pilot and one passenger sustained fatal injuries; the airplane sustained substantial damage to the wings and fuselage from impact forces. The cross-country personal flight departed Chandler, Arizona, at an undetermined time with a planned destination of North Las Vegas Airport (VGT), Las Vegas, Nevada. Visual meteorological (VMC) conditions prevailed, and no flight plan had been filed. Information from the Federal Aviation Administration (FAA) indicated that the pilot contacted Las Vegas Terminal Radar Approach Control (LAS TRACON). The airplane was at 9,500 feet mean sea level (msl); the pilot requested priority handling because an engine chip light had illuminated. Shortly thereafter, the pilot stated that he had lost a cylinder, and declared an emergency. He said that he was going to attempt to land at Boulder City Municipal Airport (BVU), and the controller approved him to switch to the BVU common traffic advisory frequency (CTAF). Prior to switching frequencies, the pilot reported that the airplane was at 3,800 feet with the landing gear down, and the situation was under control. There was no other contact from the pilot with TRACON or on the CTAF. The airplane collided with terrain about 1 mile west of the airport. PERSONNEL INFORMATIONA review of Federal Aviation Administration (FAA) airman records revealed that the 41-year-old pilot held a commercial pilot certificate with ratings for airplane single-engine land, rotorcraft-helicopter, lighter-than-air balloon, and instrument airplane. The pilot had a certified flight instructor (CFI) certificate with ratings for airplane single-engine land and ground instructor-advanced. He additionally held an Airframe and Powerplant (A&P) certificate with Inspection Authorization (IA). The pilot was issued a second-class medical certificate on November 22, 2011, with no limitations. No personal flight records were located for the pilot. The National Transportation Safety Board (NTSB) investigator-in-charge (IIC) obtained the aeronautical experience listed in this report from a review of the FAA airmen medical records on file in the Airman and Medical Records Center located in Oklahoma City. The pilot reported on his medical application that he had a total time of 945 hours with 250 hours logged in the previous 6 months. AIRCRAFT INFORMATIONThe airplane was a Beech A45, serial number G-756. A review of the airplane's logbook revealed that the original logbooks were lost; the current logbook was started on July 3, 1993, at a total time of 5,335.4 hours and a tachometer time of 581.4 hours. The tachometer read 691.5 at the last annual inspection on March 1, 2012. The engine was a Continental Motors, Inc. (CMI), IO-550-B23B, serial number 296827-R. It was a factory remanufactured 0-time engine, and was installed on the airplane on June 21, 1996. A new hour meter was installed on May 5, 1997, that read 32.0 hours; this was to match the hour meter with the engine total time of 32.0 hours. The pilot was performing maintenance on the airplane under his mechanic authorization. An annual inspection was in progress, and work completed included replacement of all six cylinders with new cylinders. He had flown the airplane to Chandler for a required maintenance inspection of the wings the day before the accident, and was returning to North Las Vegas. Written communication between the pilot/mechanic and the owner of the airplane indicated that, 3 days prior to the accident, the engine had been operated. It ran well, and the airplane was nearly ready for flight. An email to the owner the evening before the accident stated that the inspection in Chandler had been difficult, because the pilot/mechanic had spent a lot of time looking for tools and parts. The email stated that the plan was to return the airplane to North Las Vegas the following day. It noted that the airplane was flying great, and the cylinder head temperatures were coming down and equalizing. The pilot/mechanic said that the plan (for the day after the accident) was to complete all paperwork and billing for the work performed, and return the airplane to service. METEOROLOGICAL INFORMATIONAn aviation routine weather report (METAR) for BVU, (elevation 2,201 feet) was issued at 1435. It stated: wind from 140 degrees at 25 knots gusting to 30 knots; visibility 10 miles; sky clear; temperature 36/97 degrees Celsius/Fahrenheit; dew point -3/27 degrees Celsius/Fahrenheit; altimeter 29.67 inches of mercury; and 8 percent relative humidity. AIRPORT INFORMATIONThe airplane was a Beech A45, serial number G-756. A review of the airplane's logbook revealed that the original logbooks were lost; the current logbook was started on July 3, 1993, at a total time of 5,335.4 hours and a tachometer time of 581.4 hours. The tachometer read 691.5 at the last annual inspection on March 1, 2012. The engine was a Continental Motors, Inc. (CMI), IO-550-B23B, serial number 296827-R. It was a factory remanufactured 0-time engine, and was installed on the airplane on June 21, 1996. A new hour meter was installed on May 5, 1997, that read 32.0 hours; this was to match the hour meter with the engine total time of 32.0 hours. The pilot was performing maintenance on the airplane under his mechanic authorization. An annual inspection was in progress, and work completed included replacement of all six cylinders with new cylinders. He had flown the airplane to Chandler for a required maintenance inspection of the wings the day before the accident, and was returning to North Las Vegas. Written communication between the pilot/mechanic and the owner of the airplane indicated that, 3 days prior to the accident, the engine had been operated. It ran well, and the airplane was nearly ready for flight. An email to the owner the evening before the accident stated that the inspection in Chandler had been difficult, because the pilot/mechanic had spent a lot of time looking for tools and parts. The email stated that the plan was to return the airplane to North Las Vegas the following day. It noted that the airplane was flying great, and the cylinder head temperatures were coming down and equalizing. The pilot/mechanic said that the plan (for the day after the accident) was to complete all paperwork and billing for the work performed, and return the airplane to service. WRECKAGE AND IMPACT INFORMATIONThe IIC and inspectors from the FAA examined the wreckage at the accident scene. Detailed on site notes are in the public docket. The first identified point of contact (FIPC) was a circular ground scar with a narrow ground scar to the right that was perpendicular to the debris path and about 21 feet long. The orientation of the fuselage was opposite the direction of the debris path. The debris field was about 80 feet long by 80 feet wide. The separated propeller hub with the spinner and all three blades attached was in the FIPC. A few feet away was the separated and deformed connecting rod for cylinder number six. Six feet into the debris field was cylinder number six, which had separated. The main wreckage was 34 feet past the FIPC, and consisted of the engine and airframe. A few small parts separated, and were scattered throughout the debris field. The rear canopy was one of the most distant parts at 76 feet past the FIPC along the debris path centerline. The front of the airplane sustained severe upward crush damage. The forward fuselage and wings were crushed up about 45 degrees. The nose landing gear separated, and was in the first part of the debris field. Both main landing gear remained attached, and were extended. Both flaps were in an extended position, and sustained upward crush damage to their trailing edges. The left horizontal stabilizer, elevator, and the trim tab all sustained crush damage. There were chevrons from the outboard leading edge toward the center inboard trailing edge. The inboard forward portion of the left side was coated with a black viscous substance. The right horizontal stabilizer and rudder appeared to be undamaged. MEDICAL AND PATHOLOGICAL INFORMATIONThe Clark County Coroner completed an autopsy on the pilot, and determined that the cause of death was blunt force trauma. The FAA Forensic Toxicology Research Team, Oklahoma City, Oklahoma, performed toxicological testing of specimens of the pilot. Analysis of the specimens contained no findings for carbon monoxide, volatiles, or tested drugs. They did not perform a test for cyanide. TESTS AND RESEARCHFollow Up Examination Investigators from the NTSB and CMI examined the wreckage at Air Transport, Phoenix, Arizona, on June 26, 2013. A full report is contained within the public docket for this accident. Airframe Flight control continuity was established from the control surfaces to the deformed cockpit area. All identified push-pull tubes that connected the front and cockpit flight controls were bent or buckled, and many had fractured and separated along jagged and angular planes. Engine Numerous metal chunks were in the oil sump. Metal flakes contaminated the oil filter element, and metallic debris was on the chip detector. The airplane was equipped with a warning light annunciator panel that included two chip lights. The panel was sent to the NTSB Office of Research and Engineering for examination. The filaments in both chip light bulbs exhibited stretching. Filaments for all of the other lights were intact and unstretched. A JPI EDM-700 engine monitoring unit was installed in the airplane. This unit did not have recording capability, and no accident data was available. NTSB Materials Laboratory Examination The NTSB Materials Laboratory examined the number six cylinder and other engine components. A complete report is in the public docket. As part of the engine design, the number six cylinder was attached to the crankcase by six case studs and two through bolts that passed through the base flange of the cylinder. The cylinder was designed to be further clamped to the case by a deck plate on a 7th stud located between the number six and number four cylinders. The two through bolts passed through the forward flange of the number six cylinder and through the number four main bearing. The follow up examination determined that the nuts were missing from the through bolts on the number six side of the cylinder. Threads of both bolt ends showed radially oriented contact damage, but no overall outward shearing or deformation of the thread forms. The aft upper stud had been pulled from the case, and retained in the flange of the cylinder; its nut remained fully threaded onto the stud. Approximately four or five case threads were stripped from the crankcase with the thread remnants retained in the stud threads. The cylinder fins directly outboard of this stud were deformed consistent with contact with the end of the stud. The examination revealed that the 7th stud had its nut present, but not the deck plate that in normal assembly was under the nut and in contact with the adjacent cylinder flange. The metallurgical exam noted that the stud appeared intact with the stud threads showing some contact deformation on the number six cylinder side. The contact area was in an area that in normal assembly was concealed by the deck plate. Visual examinations of the mounting pad for cylinder number six revealed areas of fretting damage adjacent to both through bolts, at the two forward studs, and the two remaining upper studs. The pad surface at the lower two rear studs had a raised lip of material corresponding to the edge of the cylinder, and this was consistent with the cylinder rocking towards those studs.
The pilot/mechanic's loss of control during an emergency descent following a loss of engine power while in cruise flight. Contributing to the accident was the pilot/mechanic's incorrect assembly of the No. 6 cylinder at the last cylinder change, which resulted in a separation of the cylinder and the loss of engine power.
Source: NTSB Aviation Accident Database
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