Eugene, OR, USA
N95840
CESSNA 152
The flight instructor and the student pilot were part of a community college flight technology department, and the airplane was owned and maintained by the department. The flight instructor reported that, when he conducted the airplane's first flight of the day, he took off with the fuel tanks completely full. The airplane was then used for another flight; the airplane was operated for a total of 2.5 hours after the most recent refueling. Based on both that time and his visual inspection of the fuel tanks, the instructor determined that there was sufficient fuel for 2 more hours of flight, and he and the student pilot then departed in the airplane for some basic airwork. About 42 minutes into the flight, while returning to the airport for landing, the engine experienced a power loss, and the instructor conducted a forced landing in a field about 8 miles from the airport. Examination of the airplane revealed that the total quantity of fuel remaining onboard was about 1.5 gallons, which was the same as the manufacturer's designated amount of unusable fuel. A small quantity of fuel was observed in the lower cowl, but this appeared to be consistent with spillage from the carburetor as a result of the accident. No other evidence of any in-flight or postimpact fuel leaks was observed. Postaccident engine examination did not reveal any anomalies that would have contributed to the power loss. Review of the airplane's calculated average fuel consumption rates for several recent flights revealed that the rates were consistent with the manufacturer's published data. However, the calculated fuel consumption rate during the flights since the last refueling was significantly higher than other recent flights and the manufacturer's data. Despite the industry-accepted unreliability of fuel quantity indication observations, the instructor's observation of slightly less than half full tanks before the accident flight confirmed his calculations and would have resulted in 2 hours of flying time. These calculations and the instructor's observation support the validity of his preflight planning, decisions, and actions. Although uncertainties regarding initial fuel quantity, on-site spillage, and postaccident recovered fuel quantity reduced the fidelity of that calculated value, slightly more than half of the usable fuel would have to be unaccounted for, which seems unlikely. The available evidence was insufficient to enable a determination for the reason(s) for the fuel exhaustion and subsequent engine power loss.
**This report was modified on April 16, 2015. Please see the public docket for this accident to view a record of the changes made.*** HISTORY OF FLIGHT On September 28, 2012, about 1715 Pacific daylight time, a Cessna 152, N95840, was substantially damaged during a forced off-airport landing in Eugene, Oregon, following a complete loss of engine power during cruise flight. Both the certificated flight instructor (CFI) and the student pilot received minor injuries. The instructional flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no Federal Aviation Administration (FAA) flight plan was filed for the flight. The airplane was based at Mahlon Sweet Field Airport (EUG) Eugene, and was owned and operated by Lane Community College (LCC) in Eugene. According to the CFI, he was providing primary instruction to the student pilot, who had a total flight experience of about 2 hours. They had filed a flight plan with LCC, with a planned duration of about 1 hour. They departed EUG, and conducted basic airwork several miles south of EUG. When the hour meter indicated that they had been operating for about 0.6 to 0.7 hours, they began their return to EUG, and advised approach control of their intentions. When the airplane was about 10 miles south of EUG, the engine "sputtered," and the engine speed decreased to about 1,900 rpm. The CFI took control of the airplane, verified the fuel selector and throttle positions, and applied carburetor heat. The rpm decreased further, and about 2 to 3 minutes later, the engine ceased developing power. They declared an emergency to air traffic control, and the CFI identified a field suitable for an off-airport landing. Just as the airplane reached the field, they spotted powerlines, and the CFI turned the airplane to the right to avoid the powerlines. According to the CFI, the airplane "partially stalled" and landed "hard." It bounced back into the air, touched down again, and shortly thereafter, struck a ditch. The airplane came to rest about 100 feet beyond the ditch. The CFI shut down the airplane, and both occupants were able to exit the airplane on their own. PERSONNEL INFORMATION The CFI held multiple certificates and ratings, including flight instructor, airplane single engine. He indicated that he had a total flight experience of about 314 hours, including about 85 hours in the accident airplane make and model. His most recent flight review was completed about 3 weeks prior to the accident, and his most recent FAA first-class medical certificate was issued in January 2011. The student pilot had a total of about 2 hours of flight experience, all of which was in the accident airplane make and model. AIRCRAFT INFORMATION Federal Aviation Administration (FAA) information indicated that the airplane was manufactured in 1985, and was equipped with a Lycoming O-235 series engine. The airplane was maintained under a progressive inspection program by personnel from the owner/operator, LCC. The airplane was equipped with two fuel tanks, one in each wing. Total fuel capacity was 26 gallons, with a usable fuel capacity of 24.5 gallons. An electric fuel quantity gauge for each fuel tank was installed in the instrument panel. The fuel tanks were not equipped with "tabs" or other means to assist in visually gauging fuel quantity in the tank. The fuel selector valve had two positions, ON and OFF. The electrically-driven flaps were controlled by a switch/handle in the cockpit. At the time of the accident, the airframe had accumulated a total time (TT) in service of 10,098 hours. The engine had a TT of 6,454 hours, which was 1,025 hours since its most recent overhaul. The most recent inspection was completed on July 18, 2012; the airplane had accumulated about 35 hours since that inspection. About 6 weeks prior to the accident, a new #2 cylinder exhaust riser and an overhauled carburetor were installed. The airplane had accumulated about 32 hours since those maintenance actions. METEOROLOGICAL INFORMATION The EUG 1654 automated weather observation included winds from 020 degrees at 8 knots, visibility 10 miles, broken cloud layer at 25,000 feet, temperature 28 degrees C, dew point 9 degrees C, and an altimeter setting of 29.93 inches of mercury. Temperature and dew point values for the approximate time and location of the power loss indicated that the relative humidity was approximately 32 percent. When the intersection of the two temperature values was located on a chart that depicted carburetor ice envelopes, the point was in the region of the chart denoted as "Icing (glide and cruise power)," near the boundary of the region denoted as "Serious Icing (glide power)." WRECKAGE AND IMPACT INFORMATION The airplane came to rest essentially upright in a grassy field, approximately 8 miles southwest of EUG. The right main landing gear wheel and tire had separated from the gear leg, and the nose gear had collapsed. The engine cowling was crushed, and the engine mount was deformed. The propeller damage was consistent with the engine not developing power at the time of impact. The right wingtip and right horizontal stabilizer incurred minor crush damage, but the right wing was partially separated from the fuselage at the wing root. Neither wing tank was breached, and no fuel lines were disrupted. The aft fuselage sustained significant fracture and buckling damage. There was no fire. An individual who falsely identified herself to law enforcement officers as a mechanic for LCC arrived on scene very soon after the accident, and despite explicit instructions and admonitions from those officers, who were attempting to preserve the evidence, the individual accessed the airplane multiple times. The individual was neither an employee nor a representative of LCC, and did not respond to the scene at the request of, or on behalf of, LCC. The officers observed the individual reaching into the engine compartment and the cockpit. The investigation was unable to determine what changes, if any, the individual made to the cockpit configuration. Both fuel caps were observed to be in place and secured. The FAA inspector confirmed continuity between the cockpit engine controls and their respective components in the engine compartment. The engine was able to be rotated by hand. No evidence of any pre-impact deficiencies or failures that would have precluded continued operation was observed, and no additional examination or testing of the engine was conducted. Post-impact examinations by LCC, law enforcement, and FAA personnel all indicated the presence of very little fuel, and no evidence of any significant fuel spills or leaks. The fuel line between the gascolator and the carburetor was undisturbed by the accident, and there was no fuel found in that line. The gascolator was equipped with a metal bowl, and was damaged but not leaking. The FAA inspector removed the bowl. There was no fuel or any contamination inside the bowl. The recovery personnel determined that the left tank was empty, and that they recovered about 1.5 gallons total from the right tank and the fuel lines. The wing flaps were found in the fully retracted position, but the cockpit handle was near the full-down position. According to the CFI, he had placed the flap handle to the full-down position, but observed that the flaps did not extend, and he was uncertain as to why. The flap position indicator mechanism, which mechanically interacts with the cockpit flap handle to control flap position, was significantly disrupted at the rear spar. The disruption was attributed to impact damage. The investigation was unable to determine when the airplane master electrical switch was turned off, which would have prevented operation of the flaps. The investigation was unable to determine the reason for the discrepancy between the flap and flap handle positions. ADDITIONAL INFORMATION Overall Airplane Condition Several items of evidence were consistent with the airplane not being well-maintained. According to the FAA inspector who examined the airplane after the accident, his impression was that the airplane condition was indicative of substandard maintenance. He noted that there was a considerable amount of non-accident-related "debris" and corrosion inside the airplane. Significant and unusual amounts of corrosion are evident in photographs of the airplane interior structural surfaces. The inspector noted, and photographs substantiate, that there was "putty" protruding from the threads of the line fitting that threaded into the gascolator. In addition, there was a significant crack in the clamp that secured the exhaust stack from the #1 (front right) cylinder to the muffler. That crack measured approximately 1.5 inches long, and extended through about 90 percent of the clamp width. The inspector qualified the crack as "not recent," in view of both its size, and the fact that one of the clamp nuts exhibited significant thermal damage and erosion from leaking exhaust gases. Airplane Fuel Quantity Information According to the Cessna Pilot's Operating Handbook (POH), based on the size of the fuel tanks, the airplane was equipped with a "standard," as opposed to a "long range," fuel system. Fuel quantity was measured by a float-type transmitter in each tank, and each transmitter provided an electrical signal to a dedicated cockpit fuel quantity indicator. The POH stated that "when an indicator shows an empty tank, approximately .75 gallon remains in" each tank as unusable fuel. It also stated that "the "indicators cannot be relied upon for accurate readings during skids, slips, or unusual attitudes." Step 6 of the "CABIN" subsection of the "Preflight Inspection" checklist in the POH Section 4 (Normal Procedures) stated "Fuel Quantity Indicators – CHECK QUANTITY." Step 5 of the "LEFT WING" subsection, and step 1 of the "RIGHT WING" subsection, stated "Fuel Quantity – CHECK VISUALLY for desired level." The POH did not contain any fuel quantity guidance in the amplified procedures section. An LCC-produced, compact checklist provided fuel quantity guidance similar to that in the POH checklists. It did not contain any additional or amplified information regarding fuel quantity. Pilot's Handbook of Aeronautical Knowledge The FAA Pilots Handbook of Aeronautical Knowledge contained the following guidance regarding cockpit fuel gauges: "Aircraft certification rules require accuracy in fuel gauges only when they read "empty." Any reading other than "empty" should be verified. Do not depend solely on the accuracy of the fuel quantity gauges. Always visually check the fuel level in each tank during the preflight inspection, and then compare it with the corresponding fuel quantity indication." FAA SAIB CE-03-43 In September 2003, the FAA issued a revised version of its original June 2003 SAIB (Special Airworthiness Information Bulletin) CE-03-43, which informed owners and operators of Cessna propeller-driven airplanes of a "safety concern...regarding resistance and capacitance type fuel quantity gauging systems." Per the SAIB, the SAIB is for "information only," and its recommendations "are not mandatory." The SAIB referenced Cessna Service Bulletin SEB99-18 as its basis, and advised that "Cessna has expressed concern regarding airworthiness issues with resistance type fuel quantity systems on their general aviation single and multiple engine aircraft products. They recommend periodic calibration checks of both the empty and full positions of the gauging system." The SAIB recommended that an "FAA-certificated mechanic or repair station accomplish" a fuel system calibration "within the next 100 hours of operation or at the next annual inspection" to ensure that the fuel quantity system indicates "0 or empty" with only unusable fuel onboard. The SAIB further recommended that the "calibration procedure should also be performed by a properly FAA certificated mechanic or repair station at 5-year intervals or anytime the fuel gauging system components are disturbed or any time accuracy is suspect." Cessna SEB99-18 In April 2001, Cessna issued Single Engine Service Bulletin SEB99-18 Revision 1, which revised the original November 1999 edition. The original SEB only applied to airplanes equipped with Stewart-Warner brand fuel quantity indication systems, but the revised SEB removed that restriction. The SEB called for an "inspection" to verify "that each fuel tank quantity gauge indicates empty when the fuel tank contains only unusable fuel and indicates full when the fuel tank is full." The SEB cautioned that "non-compliance...may result in an incorrect fuel quantity indication," and that "Failure to resolve incorrect fuel quantity indications as well as improper preflight inspections and in-flight planning by the pilot could allow depletion of the airplane fuel supply and subsequent loss of engine power." The SEB specified that the inspection was to be "accomplished within the next 100 hours of operation or 12 months, whichever comes first," and mandated a repetitive inspection every 12 months, independent of previous inspection results. The SEB stated that compliance was "mandatory," and that the maintenance records should include the inspections accomplished, as well as when the next inspection was due. The maintenance records provided by the operator did not contain sufficient detail to determine SEB compliance. Cessna Service Manual The Cessna Service Manual applicable to the airplane contained an inspection section which enumerated systems and components, along with their specified service intervals. The "Fuel System" section contained ten line items, but none of those original ten entries concerned the fuel quantity indication system. A revision page dated January 2000 added an eleventh item, which required compliance with SEB99-18 for airplanes equipped with Stewart-Warner brand fuel quantity indication systems. According to a Cessna representative, the Service Manual was not specifically updated to incorporate SEB guidance. Instead, Cessna sends out notification of SEBs to the registered owners, and maintains all the SEBs and other guidance on the "CESVIEW server." The maintenance records provided by the operator did not contain sufficient detail to determine Service Manual compliance with regard to the fuel quantity indication system. Manufacturer's Fuel Consumption Information Section 5 (Performance) of the POH presents range, endurance, and fuel consumption information for flight planning purposes. The "Time, Fuel, and Distance To Climb" chart stated that a value of 0.8 gallons was to be used for "start, taxi, and takeoff allowance," and indicated that a fuel consumption rate during climb would be at least 8 gallons per hour (gph). Cruise fuel consumption rates, which were predicated on "recommended lean mixture," ranged between 4.2 and 6.4 gph as a function of altitude, power setting, and temperature. The "Endurance Profile" chart for standard fuel tanks presented a time vs. altitude envelope for three different power setting values. The chart depicts maximum endurance values of 4.3, 3.6, and 3.1 hours for power settings of 55, 65, and 75 percent, respectively. NTSB Fuel Consumption Calculations The LCC Director provided some historical fuel and flight time data for the accident airplane. The actual hour meter reading values for either the flights or the refueling events were not provided, which prevented independent verification of the flight durations, and also prevented integration of the flight and refueling data. This limited both the number and fidelity of the fuel consumption calculations that could be made. Data from the 5 days prior to the accident indicated that there were a total of 3 refuelings and 14 operations. Thirteen of the operations were flights, while one, with a duration of 0.9 hours, was categorized as "other" by LCC. No further definition of that event was obtained. The data, including the accident flight, indicated that a total of 66.6 gallons was consumed in a total of 15.6 hours of operation, which resulted in a calculated average fuel consumption rate of 4.3 gph.
A total loss of engine power due to fuel exhaustion during cruise flight for reasons that could not be determined because postaccident examination did not reveal any anomalies that would have resulted in the loss of engine power.
Source: NTSB Aviation Accident Database
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