Spring, TX, USA
N555UF
CESSNA 152
The purpose of the night instructional flight was to in remain in the airport traffic pattern and practice touch-and-go landings. According to air traffic control data, during the initial climb following the second touch-and-go landing, the flight instructor told the tower controller that the airplane was experiencing "engine problems" and requested to make an immediate 180-degree turn back to the airport for landing. Based on available radar data, the airplane was likely less than 250 ft above the ground when the flight instructor reported the engine problem. A witness reported that, while the airplane was on the downwind leg for the first landing, the engine sounded abnormal and that the engine continued to run roughly while the airplane was on initial climb following the second landing. Several witnesses reported seeing the airplane in a steep left turn before it entered a near-vertical descent into terrain. A postaccident airframe examination did not reveal any malfunctions or failures that would have precluded normal operation. The carburetor heat control was found in the "off" position. Control cable continuity was confirmed between the carburetor heat box and the cockpit control; however, impact damage to the carburetor air box precluded a determination of whether the carburetor heat was activated at the time of the accident. Although the weather conditions at the time of the accident were conducive to the formation of carburetor ice at reduced engine power settings, the investigation was unable to determine to what extent carburetor ice might have formed during the accident flight. Additionally, disassembly of the carburetor revealed that one of its two hollow polymer floats was flooded with fuel, which would reduce the buoyancy of the float and could result in poor idle power performance and/or possible flooding of the carburetor. During the 5 years preceding the accident, the carburetor manufacturer issued multiple service bulletins (SB) that acknowledged that the hollow polymer float design had known issues with fuel leaking into the float through a welded seam. The carburetor manufacturer specified that all affected carburetors should be inspected within 30 days and then at 30-day intervals until the affected floats were replaced with an updated solid-epoxy float design that was impervious to flooding. Owner/operator compliance with the service bulletins was considered optional under FAA regulations. According to maintenance documentation, the accident carburetor had not been inspected as specified by the SBs. Ultimately, the root cause for the partial loss of engine power could not be identified because the investigation was unable to determine to what extent carburetor icing, the flooded float, or a combination of the two conditions could have contributed to the loss of engine power. Following the partial loss of engine power, it is likely that the flight instructor failed to maintain airspeed during the turn back to the airport, which resulted in an aerodynamic stall.
HISTORY OF FLIGHTOn November 17, 2013, at 1915 central standard time, a Cessna model 152 airplane, N555UF, was substantially damaged during a forced landing at the David Wayne Hooks Memorial Airport (DWH), Spring, Texas. The flight instructor and student pilot were fatally injured. The airplane was registered to WBR Interests LLC and operated by United Flight Systems, under the provisions of 14 Code of Federal Regulations Part 91, without a flight plan. Night visual meteorological conditions prevailed for the local area training flight that had departed DWH at 1900. According to air traffic control (ATC) data, the purpose of the instructional flight was to remain in the airport traffic pattern to practice night takeoffs and landings. At 1900:22, the tower controller cleared the accident flight for takeoff and to remain in a left traffic pattern for touch-and-go landings on runway 17R (7,009 feet by 100 feet, asphalt). The accident airplane was first observed on radar about 150 feet above ground level (agl) while on the upwind leg. The airplane continued to make left traffic for runway 17R before being cleared for the first touch-and-go landing at 1904:42. At 1906:48, the airplane descended below available radar coverage while on a 1/4 mile final for runway 17R. The airplane reemerged on radar at 1908:15, about 1/4 mile south of the runway departure threshold at about 250 feet agl. The airplane continued to make left traffic for runway 17R before being cleared for the second touch-and-go landing at 1911:08. At 1913:48, the last radar return was recorded for the accident flight about 1/3 mile north of the runway approach threshold at about 150 feet agl. At 1914:41, the flight instructor told the tower controller that they were having "engine problems" and requested to make a 180-degree turn back to the airport for a landing. At 1914:47, the tower controller cleared the flight for the 180-degree turn back landing. Based on available information, the airplane had completed the second touch-and-go landing and was on initial climb when the flight instructor reported the loss of engine power. At 1914:51, there was an open-microphone transmission from the accident airplane that comprised of "No, No, My." No additional transmissions were received from the accident flight. The tower controller reported that after he cleared the flight for the 180-degree turn back landing, he saw the airplane enter a steep left bank and descend nose-down into the terrain located on the east side of the airport. Another witness reported hearing the accident airplane while it was on a left downwind leg for runway 17R and remarked that the sound of the engine was abnormal. The same witness reported that the engine continued to run rough while the airplane was on initial climb following the second touch-and-go landing. Several witnesses to the accident reported seeing the accident airplane in a steep left turn before it entered a near vertical descent into terrain. Two of these witnesses reported seeing the wingtip navigation and strobe lights in a near vertical line, indicating a near 90-degree bank angle, before the airplane banked past 90-degrees and descended nose-down into the terrain. PERSONNEL INFORMATION--- Flight Instructor --- According to Federal Aviation Administration (FAA) records, the flight instructor, age 22, held a commercial pilot certificate with single and multi-engine land airplane and instrument airplane ratings. He also held a flight instructor certificate with single engine airplane and instrument airplane ratings. His last aviation medical examination was completed on May 23, 2013, when he was issued a second-class medical certificate with no limitations or restrictions. A search of FAA records showed no previous accidents, incidents, or enforcement proceedings. His last flight review, as required by FAA regulation 61.56, was completed upon the reissuance of his flight instructor certificate dated September 6, 2013. The flight instructor's flight history was reconstructed using pilot logbook information and employment documentation. He had been employed by the airplane operator, United Flight Systems, since October 11, 2013. His most recent pilot logbook entry was dated November 15, 2013, at which time he had accumulated 332.4 hours total flight time, of which 247.9 hours were listed as pilot-in-command. He had accumulated 290.6 hours and 40.6 hours in single engine airplanes and multi-engine airplanes, respectively. He had logged 166 hours of flight time in Cessna 152 airplanes. He had logged 2.1 hours in actual instrument meteorological conditions (IMC) and 58.6 hours as simulated IMC. He had provided 63.5 hours of flight instruction since receiving his initial flight instructor certificate on August 6, 2013. He had flown 13.2 hours during night conditions. According to the logbook, there was only one logged night flight during the 12 month period before the accident flight. The night flight was completed on November 15, 2013, and included 3 landings. According to the flight instructor's logbook, he had flown 119.3 hours during the prior 12 months, 97.3 hours in the previous 6 months, 71.1 hours during prior 90 days, 65.7 hours in the previous 60 days, and 62.3 hours in the 30 day period before the accident flight. The flight instructor's logbook did not contain any recorded flight time for the 24 hour period before the accident flight; however, according to operator records, he had completed two earlier flights, totaling 2.5 hours, on the day of the accident. --- Student Pilot --- According FAA records, the student pilot, age 23, held a student pilot certificate. His last aviation medical examination was completed on July 1, 2013, when he was issued a first-class medical certificate with no limitations or restrictions. A search of FAA records showed no accident, incident, enforcement, or disciplinary actions. The student pilot was a foreign-national who was receiving flight instruction toward a pilot certificate. According to available logbook information, between February 4, 2008, and September 18, 2008, the student pilot had received basic flight instruction in the Republic of India. During this period of flight instruction, the student pilot received 21.4 hours of dual flight instruction and flew 19.6 hours solo. After September 18, 2008, there were no logged flights until the student pilot completed his first instructional flight in the United States on October 18, 2013. The student pilot received an additional 12.5 hours of dual instruction and flew 0.3 hours solo while receiving flight instruction in the United States. The student pilot's combined flight experience totaled 53.8 hours, of which 19.9 hours were logged as solo flight. All of the student pilot's flight experience had been accumulated in Cessna 152 airplanes. According to available information, the student did not have any night flight experience before the accident flight. The student pilot's logbook contained a flight instructor endorsement for solo flight in a Cessna 152 that was dated November 9, 2013. AIRCRAFT INFORMATIONThe accident airplane was a 1981 Cessna model 152 single-engine airplane, serial number 15284692. A 110-horsepower Lycoming model O-235-L2C reciprocating engine, serial number L-17634-15, powered the airplane through a fixed-pitch, two blade, McCauley model 1A103/TCM6958 propeller. The airplane had a fixed tricycle landing gear, was capable of seating two individuals, and had a certified maximum gross weight of 1,675 pounds. The accident airplane was issued a standard airworthiness certificate on October 27, 1980. The current owner-of-record, WBR Interests LLC, purchased the airplane on February 20, 2007; however, the airplane had been operated by United Flight Systems since March 15, 1993. The recording tachometer indicated 5,699.4 hours at the accident site. The airframe had accumulated a total service time of 15,699.4 hours at the time of the accident. The engine had accumulated a total service time of 5,610.4 hours at the time of the accident and 3,674.3 hours since a field overhaul that was completed on November 4, 2004. The last annual inspection of the airplane was completed on July 25, 2013, at 15,622.4 total airframe hours. On September 5, 2013, at 15,676.1 total airframe hours, the carburetor heat control cable was replaced. The last recorded maintenance was the replacement of the airplane's transponder on November 4, 2013. A postaccident review of the maintenance records found no history of unresolved airworthiness issues. The airplane had a total fuel capacity of 26 gallons (24.5 gallons useable), which was distributed evenly between two 13-gallon wing fuel tanks. A review of fueling records established that the airplane fuel tanks were topped-off before the accident flight. Following the accident, a fuel sample was collected from the truck that was used to fuel the accident airplane. The fuel sample was blue in color, consistent with 100 low-lead aviation fuel. Additionally, the collected fuel sample did not contain any particulate or water contamination. METEOROLOGICAL INFORMATIONAt 1853, the DWH automated surface observing system reported: calm wind, visibility 10 miles, sky clear, temperature 23 degrees Celsius, dew point 21 degrees Celsius, and an altimeter setting of 29.89 inches-of-mercury. The United States Naval Observatory reported that the sunset and end of civil twilight at DWH was at 1725 and 1751, respectively. The moonrise was at 1742 for the full-phase moon. The carburetor icing probability chart included in Federal Aviation Administration Special Airworthiness Information Bulletin No. CE-09-35, Carburetor Icing Prevention, indicated that the accident flight was likely operating in atmospheric conditions that were associated with a serious risk of carburetor ice accumulation while operating at reduced engine power settings. AIRPORT INFORMATIONThe accident airplane was a 1981 Cessna model 152 single-engine airplane, serial number 15284692. A 110-horsepower Lycoming model O-235-L2C reciprocating engine, serial number L-17634-15, powered the airplane through a fixed-pitch, two blade, McCauley model 1A103/TCM6958 propeller. The airplane had a fixed tricycle landing gear, was capable of seating two individuals, and had a certified maximum gross weight of 1,675 pounds. The accident airplane was issued a standard airworthiness certificate on October 27, 1980. The current owner-of-record, WBR Interests LLC, purchased the airplane on February 20, 2007; however, the airplane had been operated by United Flight Systems since March 15, 1993. The recording tachometer indicated 5,699.4 hours at the accident site. The airframe had accumulated a total service time of 15,699.4 hours at the time of the accident. The engine had accumulated a total service time of 5,610.4 hours at the time of the accident and 3,674.3 hours since a field overhaul that was completed on November 4, 2004. The last annual inspection of the airplane was completed on July 25, 2013, at 15,622.4 total airframe hours. On September 5, 2013, at 15,676.1 total airframe hours, the carburetor heat control cable was replaced. The last recorded maintenance was the replacement of the airplane's transponder on November 4, 2013. A postaccident review of the maintenance records found no history of unresolved airworthiness issues. The airplane had a total fuel capacity of 26 gallons (24.5 gallons useable), which was distributed evenly between two 13-gallon wing fuel tanks. A review of fueling records established that the airplane fuel tanks were topped-off before the accident flight. Following the accident, a fuel sample was collected from the truck that was used to fuel the accident airplane. The fuel sample was blue in color, consistent with 100 low-lead aviation fuel. Additionally, the collected fuel sample did not contain any particulate or water contamination. WRECKAGE AND IMPACT INFORMATIONA postaccident investigation confirmed that all airframe structural components and flight controls were located at the accident site. The wreckage was located on the east side of the airport, north of taxiway hotel and east of taxiway mike. The initial impact point was determined to be where the right wing collided with the northwest corner of a hangar structure. The outboard 9 feet of the right wing separated during the initial impact and was found about 90 feet northwest of the initial impact point on taxiway mike. The main wreckage, located about 29 feet north of the initial impact, consisted of the left wing, fuselage, empennage, engine, and propeller. The forward fuselage, including the cockpit, exhibited impact damage that significantly reduced the cabin volume. The left wing remained partially attached to the fuselage. The left wing had impacted a structural post and a spiral staircase that was associated with a residential hangar. The aircraft wreckage was orientated on a 035 degree magnetic heading. The fuselage was found resting on its lower surface. There was no evidence of an inflight or postimpact fire. The first responders reported that there was a substantial fuel odor at the accident site. Flight control cable continuity could not be established due to multiple separations; however, all observed separations were consistent with overstress fractures. Both flaps had separated from their respective wings; however, a flap actuator measurement was consistent with the flaps being extended between 0 degrees and 10 degrees. The measured extension of the elevator trim actuator was consistent with a nose-level attitude. The ignition/magneto switch was found selected to the left magneto. The throttle was found extended about 1-inch from a full power position. The mixture control was found in the full-rich position. The carburetor heat control was found full forward in the OFF position. The carburetor air box had been crushed during the impact sequence, which precluded a determination if the carburetor heat had been activated at the time of the accident. Control cable continuity was confirmed between the carburetor heat box and the cockpit control. The cockpit fuel shutoff handle was found in the ON position and the firewall fuel strainer contained fuel. A fuel sample obtained from the fuel strainer exhibited no indication of water contamination when exposed to water detection paste. The fuel primer was found full forward and secured. The stall warning horn sounded when a vacuum was applied to the leading edge inlet. The engine remained attached to the firewall by its mounts and control cables. Mechanical continuity was confirmed from the engine components to their respective cockpit controls. Internal engine and valve train continuity was confirmed as the engine crankshaft was rotated. Compression and suction were noted on all cylinders in conjunction with crankshaft rotation. The spark plugs were removed and exhibited features consistent with normal engine operation. Both magnetos provided spark on all leads when rotated by hand. All four engine cylinders were removed and no anomalies were noted with the cylinders, valves, pistons, connecting rods, or crankshaft. There were no obstructions between the air filter housing and the carburetor. The carburetor fuel bowl contained a liquid that was consistent with the color and odor of 100 low-lead aviation fuel. The fuel sample obtained from the carburetor bowl did not exhibit any water or particulate contamination. The Precision Airmotive model MA-3A carburetor, p/n 10-5199, s/n CR15409, was equipped with white, hollow, polymer floats (p/n 30-804). One of the two floats was found flooded with a blue fluid that was consistent with 100 low-lead aviation fuel. The second float was void of any fuel. The propeller remained partially attached to the engine crankshaft flange. Both propeller blades exhibited minor leading edge damage. One propeller blade exhibited chordwise scratches. Neither blade exhibited appreciable spanwise bends or blade twist. ADDITIONAL INFORMATIONOn January 30, 2008, Precision Airmotive LLC, the manufacturer of the MA-3A carburetor, issued Mandatory Service Bulletin No. MSA-13 that required the replacement of brass and polymer hollow floats with a new solid-epoxy float design. According to the service b
The flight instructor's failure to maintain airspeed following a partial loss of engine power for reasons that could not be determined during postaccident examination, which resulted in an aerodynamic stall and subsequent loss of airplane control.
Source: NTSB Aviation Accident Database
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