Rancho Cucamong, CA, USA
N2733Y
Beech 95
While in cruise flight, a portion of a propeller blade separated from the right engine. The resulting vibration partially separated the engine from its airframe mounts, and the uncontrollable airplane rolled inverted and dived into a private residence. The house was severely damaged, the airplane was destroyed. The separated propeller was overhauled about 3 years and 5 operational hours prior to the accident flight. The separated 2.5-foot-long span of the failed blade was found about 1 mile from the main wreckage. The blade was examined by the NTSB's Metallurgical Laboratory, which found that the blade failed as a result of fatigue cracking initiated by corrosion pitting in the pilot tube bore. A fatigue crack had initiated at two corrosion pit sites in the bore, which had been painted over without the corrosion being dressed out during the overhaul. Also, many additional corrosion pits were located circumferentially in line with the origin area. The blade's bore was also contaminated with glass beads. All of these conditions found during the examination were contrary to the procedural steps in the manufacturer's overhaul instructions, and established that the blade was reassembled with an incomplete and improper overhaul. The FAA inspector assigned to oversee the overhaul company said he did not observe any repair station deficiencies during his surveillance inspections. A Safety Board inspection following the accident disclosed that the repair station's personnel were not following prescribed manufacturer overhaul procedures, did not have the required chemicals for blade treatment, and did not possess required procedure manuals. Additional inspections of other propellers overhauled by the company revealed that propellers overhauled as early as 1997, when the company commenced business, showed evidence of corrosion in the pilot bores, and were unairworthy.
HISTORY OF FLIGHT On January 24, 2003, about 1626 Pacific standard time, a Beech 95, N2733Y, experienced the in-flight separation of one right engine propeller blade, which was followed by the engine dislodging from its firewall mounts. The pilot was unable to maintain controlled flight, and the airplane descended into a private residence in Rancho Cucamonga, California. The sole occupant in the house was not injured. The airplane was destroyed, and its private pilot, the sole occupant in the airplane, was fatally injured. The pilot co-owned and operated the airplane. The personal flight, which was reportedly the first following maintenance, was performed under the provisions of 14 CFR Part 91. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated from the (uncontrolled) Cable Airport, Upland, California, about 1620. The airplane departed from runway 24 and climbed to about 4,500 feet mean sea level. A pilot who was flying in the area observed the Beech and noticed it suddenly made a steep turn. Subsequently, the airplane descended. Several ground-based witnesses who noted smoke trailing from the airplane observed the descent. One witness reported observing the right engine hanging straight down toward the ground with the propeller stopped. Thereafter, the airplane rolled over until becoming upside down, and it dove straight toward the ground. Several other witnesses also reported observing the airplane in a steep right bank turn and then a nosedive toward the ground. The airplane's descent terminated when it impacted a house in a near vertical nose down attitude. OTHER DAMAGE A single family residence was partially destroyed. PERSONNEL INFORMATION Pilot. The pilot held a private pilot certificate with airplane single and multiengine land ratings. He also held an aircraft repairman certificate, which was issued on January 6, 1998. The repairman certificate was valid for troubleshooting, inspection, and maintenance of aircraft, airframe, and engines while employed by Foothill Aircraft Sales and Service, Inc., Upland. The pilot's previous aircraft repairman certificate was issued on July 24, 1981. The pilot's flight time and currency information was provided by acquaintances of the pilot and by the Federal Aviation Administration (FAA). The pilot's personal flight record logbook was not provided for examination, and his recent flying experience/currency was not confirmed. The pilot's flight hours reported herein are derived from the aforementioned sources and Safety Board investigator estimates. Acquaintances reported they believed the pilot's total flight time was about 3,000 hours; his flying activity during the preceding 90 days was 40 hours, and his experience flying the Beech 95 was 25 hours. According to FAA airmen medical records, on medical certificate applications dated 9/19/2002, 7/3/2000, and 4/14/1998, the pilot reported that his total flight times were 3,000, 1,200, and 1,800 hours, respectively. On these dates, the pilot also reported that his flying activity during the preceding 6 months was 80, 15, and 10 hours, respectively. AIRCRAFT INFORMATION The Beech 95 (Travelair), serial number TD-72, was manufactured in 1958, and was issued a standard FAA airworthiness certificate. The airplane's two 180 hp Lycoming O-360-AIA engines are equipped with 2-bladed, single acting, hydraulically operated, constant speed, full feathering Hartzell propellers, model HC-92ZK-2. The propellers are manufactured with 8447-12(A,R) blades (Z-shank). This designation identifies them as steel hub, single shoulder blades with internal bronze bushings. Z-shank blades are manufactured from a one-piece aluminum forging. The hub and blade clamps are steel. Oil pressure from the propeller governor is used to move the blades to the low pitch (blade angle) direction. Blade mounted counterweights and feathering springs actuate the blades towards the high pitch/feather direction in the absence of governor oil pressure. Propeller rotation is clockwise as viewed from the rear. Propeller Installation. The National Transportation Safety Board investigator reviewed the airplane, engine, and propeller logbooks provided by the airplane owner's attorney and by the owner of T & W Propellers. In pertinent part, airplane logbook No. 1 indicates that, in 1988, the left engine was equipped with propeller hub serial number (S/N) 279F. The right engine's propeller hub was S/N 282F. The left engine's propeller blade S/Ns were 113573 and 114546. The right engine's propeller blade S/Ns were 114565 and 114356. Subsequently, the left engine's hub was changed, and the two propeller blades on each of the hubs were also changed. According to the airplane's maintenance records, on the accident date the airplane was configured as follows: Left Engine, per Foothill Invoice number 5708: S/N RL-1280-36 Total Time on the Factory Remanufactured Engine: 6,668 hours Hartzell Propeller HC-92ZK-2A; Blade Design 8447-12A Hub: S/N 481F Blades Marked: S/N A49334 and S/N A49352 Right Engine, per Foothill Invoice number 5708: S/N L-501-36 Total Time on Engine: 2,383 Hartzell Propeller HC-92ZK-2B; Blade Design 8447-12R Hub: S/N 282F Blades Marked: S/N C36230 and S/N C36547 NOTE: During the wreckage examination the above listed hub/propeller assemblies were found attached to the opposite engines. The right engine's propeller hub bore S/N 481F. The butt end of the blade shank fragment that remained clamped in the hub (from the separated blade) was found stamped with S/N A49334. (In this report, this failed blade is referred to as blade "R1.") These reversed positions were not documented in the airplane logbook. No explanation was provided by maintenance personnel regarding this discrepancy. According to the Hartzell participant, Beech 95 series aircraft are approved with either 8447-12A or 8447-12R blade designs. The only difference is the blade tip shape; the -12R blade has a round tip with a relatively large tip radius. The propeller positioned on the left engine was found to have -12R blades, and the propeller positioned on the right engine had -12A blades, with a less circular tip shape. Propeller Maintenance History. On December 3, 1996, the airplane received maintenance. As indicated on Foothill Aircraft Sales & Service, Inc., invoice number 1148, at a tachometer time of 1,035 hours, the propellers were removed from the airplane and sent to Southern California Propeller Service (SCPS), which operated an FAA repair station under certificate No. VXSR617L. On Foothill's invoice number 1597, at a tachometer time of 1,435 hours, a notation appears indicating that per SCPS's invoice number 4639, the propellers had been disassembled and inspected. A notation was made that the blade shank inspection and compression roll was required every 500 hours. On December 6, 1996, SCPS, made an entry in the airplane's propeller logbook. The entry indicated that the left engine's hub S/N 481F with blades S/N A49334 and A49352, and the right engine's hub S/N 282F with blades S/N C36230 and C36547, had been "COMPLETELY REPAIRED." The maintenance was also recorded with the same date on the "Overhaul Record" page in the logbook. Also, on the "AIRWORTHINESS DIRECTIVE AND SERVICE BULLETIN/LETTER COMPLIANCE RECORD" page, the following airworthiness directives were listed as having been complied with: 95-11-08 and 85-14-10R2. According to an entry in the airplane's logbook, on December 6, 1996, the airplane received an annual inspection. Its total airplane time was listed as 9,221 hours. The next consecutive logbook entries were dated February 26, 1997; March 28, 1997; and May 23, 1997. These entries indicated performance of annual inspections. On June 10, 1997, the airplane received a 50-hour inspection. By this date the airplane's total time was listed as 9,679 hours. The owner of T & W Propellers reported that on December 10, 1999, it received the aforementioned left and right propeller hubs and blades from the airplane's owner-operator, who requested that they be overhauled. T & W Propeller's owner provided the Safety Board investigator with documents indicating that his company completed the requested propeller overhaul on January 11, 2000. Thereafter, the hubs and blades were returned to the airplane's owner. The indicated time since overhaul (TSO) was recorded as being 0.0 hours. According to the airplane's maintenance records, between May 14 and 15, 2002, the left propeller blades (from Hub S/N 481F) were installed on the airplane's left engine, and the right propeller blades (from Hub S/N 282F) were installed on the right engine. Both assemblies were dynamically balanced, and the engine was satisfactorily ground run tested. The listed time since overhaul was 0.0 hours. Subsequently, the right hub and propeller assembly were returned to T & W Propellers for correction of a vibration problem. According to the propeller logbook entry, T & W Propellers checked the blade track, angles, and balance to repair the vibration. T & W Propeller's owner reported to the Safety Board investigator that his company did not disassemble the propeller from the hub. No discrepancies were noted. That was the last time he saw the propellers. It was his understanding that the following day the assembly was reinstalled on the airplane. The logbook indicates that the assembly was dynamically balanced and satisfactorily ground run tested. The listed time was 0 hours since overhaul. The airplane's total time was listed at 9,679 hours. The airplane's maintenance record logbook indicates that the airplane's last annual inspection was completed on January 24, 2003, the day of the accident. The listed total airframe time in this logbook was still 9,679 hours. The time since the airplane's last engine and propeller overhauls was listed as 0.0 hours. Airplane Total Time Determination. The Safety Board's investigator's additional inquiry regarding the airplane's total time disclosed, on a printout entitled "Airworthiness Directive Compliance Record," dated January 17, 2003, that the airplane's Hobbs meter registered 5.0 hours. Also, the airplane's total time was listed on this record as 9,684 hours. Acquaintances of the pilot reported that when a requisite amount of engine oil pressure is produced, the Hobbs meter may activate, and this may occur during ground engine operation. Some of the maintenance records indicated that the Hobbs meter was connected to an air switch. The Safety Board investigation did not ascertain whether the accident occurred during the first flight following completion of the propeller and engine overhauls and the January 24, 2003, annual inspection, or whether it occurred during a flight commencing 5 hours thereafter. (See statements of Foothill Aircraft Sales and Service personnel for additional information regarding the airplane's maintenance and flight time history.) In summary, by the accident date, it had been about 6 years and 463 (engine) operational hours since the propellers had received maintenance from SCPS. It had been about 3 years and 5 (engine) operational hours since the propellers received an overhaul from T & W Propellers. METEOROLOGICAL INFORMATION The closest aviation weather observation station to the accident site is located at the Ontario International Airport, about 4.5 nm south (162 degrees, magnetic) of the accident site. In pertinent part, at 1553 Ontario reported the following weather conditions existed: wind from 260 degrees at 4 knots; 10 miles visibility; scattered clouds at 10,000 feet, broken ceiling at 20,000 feet; altimeter 30.04 inHg; and temperature 24 degrees Celsius. COMMUNICATION FAA Quality Assurance personnel reported that no air traffic control communications or services had been provided to the accident airplane during its flight. WRECKAGE AND IMPACT INFORMATION A 2.5-foot-long portion of one of the two right engine propeller blades separated from the remainder of the propeller, which remained secured to the propeller hub assembly. The fragment impacted terrain about 1.2 statute miles northwest (304 degrees, magnetic) from the location where the main wreckage impacted into a private residence on Cathedral Court, Rancho Cucamonga. The global positioning system coordinates for the main wreckage were about 34 degrees 07 minutes 49.5 seconds north latitude by 117 degrees 36 minutes 33.9 seconds west longitude. The elevation is about 1,515 feet mean sea level. Reports received from the San Bernardino County Sheriff's office indicated that at least six persons found debris from the airplane. The majority of the witnesses were located within about 0.25-mile from where the piece of propeller blade was found. In total, about 23 pieces of airframe components and engine accessory-related components were located in this area. The main wreckage was observed in a near vertical nose down pitch attitude, and it had penetrated the roof of a 2-story house. The nose of the airplane was at ground level. The right engine was partially separated from its firewall attachment mounts and was partially ripped out of the airframe. The left engine was secure to the airframe. All flight control surfaces were present. A pool of fuel was present on the floor of the house, beneath and surrounding the airplane. During the extrication of the airplane, the left wing was found separated from the structure outboard of the engine nacelle. The majority of the wing was destroyed, with the skin separated from the spars, and the leading edge was crushed and torn. Aileron control cable continuity was confirmed to the control linkage in the left wing. The engine and nacelle remained attached to the inboard wing portion that had remained partially attached to the fuselage. The nose of the fuselage was observed crushed in an aft direction, relative to the longitudinal axis of the airplane. The left engine gauges were observed registering 36 inches of manifold pressure and 500 rpm. The right engine gauges were observed registering 41 inches of manifold pressure and 0 rpm. The fuel selector was on the main tank position. All of the empennage flight control surfaces, hinges, cables, and counterweights were found with the main wreckage. The structure that attached the right engine to the firewall was found fractured. An oil residue was observed on the right horizontal stabilizer's leading edge, and on the stabilizer's upper and lower surfaces. The oil was noted dispersed in an aerodynamically streamlined direction. No similar oil residue was observed on the left side of the fuselage. The landing gear was in the retracted position. There was no fire. MEDICAL AND PATHOLOGICAL INFORMATION The pilot's last aviation medical certificate was issued in the third-class on September 19, 2002. No restrictions were listed. An autopsy was performed on the pilot by the San Bernardino County Coroner's Office on January 28, 2003. The FAA's Toxicology and Accident Research Laboratory, Oklahoma City, Oklahoma, performed toxicology tests on specimens from the pilot. No evidence of carbon monoxide, cyanide, ethanol, or any screened drugs was reported. TESTS AND RESEARCH Engine Examinations. In pertinent part, the Lycoming Engine participant who examined the engines and attached propeller assemblies under the Safety Board investigator's direction and observation, indicated the following with respect to the left engine: (1) The two-bladed propeller remained attached at the crankshaft flange and exhibited bending signatures consistent with torsional deformation; (2) The propeller blades remained attached to the propeller hub, and the blades exhibited leading edge gouging, torsional twisting, chordwise striations and "S" bending; (3) The carburetor bowl, oil pressure screen and induction system were free of contaminants; and (4) The spark plugs exhibited coloration consistent with normal operation (reference Champion Spark Plugs "Check-a-Plug" chart). In pertinent part, the right engine and the por
The fracture and separation of a propeller blade during cruise flight due to fatigue and corrosion pits in the blade pilot bore, and an improper overhaul of the separated propeller by repair station personnel. Factors contributing to the accident were the FAA's inadequate surveillance of the repair station, and the repair station's inadequate procedures.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
