SAN CARLOS, AZ, USA
N8KB
Beech 95-B55
The aircraft was on a routine fire reconnaissance patrol. There were no eyewitnesses to the accident. Air Route Traffic Control Center (ARTCC) radar data showed no primary or secondary targets at or above 3,000 feet AGL. No record was found that either crew member initiated an emergency transmission. No weather phenomena was observed by any source in the area. The aircraft crashed at the apex of a river bed in a narrow canyon at an elevation of 5,620 feet MSL, and came to rest on a sandbar with a measured 400-foot radius bend in the river. The wall on the west side of the river rises steeply to about 6,100 feet MSL, and the terrain on the east side rises to equal heights over a slightly longer horizontal distance. The trim speed of the aircraft was computed by Beech Aircraft at 120 knots based on the elevator trim tab position in comparison to the gross weight and CG. A 73-degree bank angle is required for the aircraft to make a 400-foot-radius turn at 120 knots. The aircraft stall speed at that bank angle is 111 knots. An extensive postcrash fire consumed the aircraft and no ground scars were observed outside of the immediate area of the main wreckage. According to a Hartzell Propeller report, both propellers were operating symmetrically at blade angles in the governed range during the impact sequence. No preimpact failures or system/component malfunctions were found. A review of past reconnaissance flights over this same route disclosed that the flight's position reports and computed ground speed was consistent with all past flights.
HISTORY OF FLIGHT On June 3, 1997, about 1040 hours mountain standard time, a Beech 95-B55, N8KB, collided with terrain during a routine fire reconnaissance of the San Carlos Indian Reservation (SCIR), San Carlos, Arizona. The aircraft was being operated by Safford Aviation, under an exclusive use contract to the Bureau of Indian Affairs as a public-use aircraft. The mission was a routine fire patrol conducted under 14 CFR Part 91 of the Federal Aviation Regulations. Visual meteorological conditions prevailed and no flight plan was filed. The aircraft was destroyed during the impact sequence and subsequent postcrash fire. The certificated commercial pilot and his observer received fatal injuries. The aircraft had previously been in contact with the San Carlos Dispatch radio operator and was giving agency flight following reports. The flight originated at San Carlos at 1007. There were no known eyewitnesses to the accident. According to the Bureau of Indian Affairs, the crew of N8KB (referred to in their logs as P-2) called the San Carlos dispatch at 1027 and reported their location was Baskin Tank, and that they were en route to Elwood Tank. The dispatcher tried to reach P-2 via aircraft radio on an agency FM frequency at 1051, and again at 1054, with no response. At 1057, another fire patrol aircraft, H350, a Bell 206L1, took off and proceeded to Coupon Tank due to black smoke being reported. At 1156, H350 landed at the incident site and discovered the downed aircraft. The aircraft came to rest in a portion of the Black River Canyon, which is located in Apache County, Arizona. A copy of the SCIR dispatch log was obtained and reviewed. The log noted in a 1007 entry "P2 off ground...enroute to Seneca." The flight was recorded as reporting "over Salt Crossing heading to Black River Crossing" at 1018. At 1027, the aircraft reported "passing Baskin Tank heading to Elwood Tank." The dispatcher tried to call P-2 again at 1051 and received no response. He tried to make radio contact with them again at 1054, without success. At 1117, the dispatchers contacted the operator of the aircraft and asked them to contact Prescott Flight Service station. According to calculations provided by the operator, at normal patrol airspeeds, the elapsed time from Baskin Tank to the crash site would have been approximately 13 minutes, with a distance traveled of about 32 miles. A thorough review of dispatch logs from all available sources revealed discrepancies with respect to the time(s) various events were noted to have occurred. The chief pilot of Safford Aviation was interviewed regarding the patrol route and the timing of the position reports. He concluded that the aircraft was on a "normal" morning reconnaissance flight and that both the route and timing of the reporting points were consistent with all other flights over the past 4 years. Additionally, he opined that "the speed of the aircraft (estimated to be an average ground speed of 145.2 mph) was within normal parameters for this mission flown." A map, which is appended to this report, depicts the actual route flown with a solid red line, and the intended route of flight with a dashed red line. Additionally, the map shows the known reporting points/timing of the accident flight. The previous 4 days worth of dispatch logs were reviewed during the investigation and they disclosed that the route and timing of the position reports were consistent with the accident flight. The FAA Air Route Traffic Control Center (ARTCC) at Albuquerque, New Mexico, controls the airspace over the area of the accident site and the patrol mission route. The Quality Assurance specialists at Albuquerque ARTCC stated that the radar coverage in the area of the accident has a general floor of 9,500 feet msl. At the Safety Board's request, Albuquerque ARTCC examined their recorded radar data for the date of the accident. For a time frame from 15 minutes before to 15 minutes after the accident, no primary or secondary 1200 beacon codes were observed. Additionally, the Jackel MOA (military operations area) was inactive from 1020 to 1350 local time. According to Prescott Flight Service station, there were no ELT signals reported at the time in question for this area. The Safety Board was informed that there were individuals present at the Black River pump station near the accident site. The occupants of the station were identified and interviewed by telephone on September 10, 1997. A witness stated that to the best of his recollection he called in and reported seeing smoke from the accident site "about 10 AM." He said he was standing out on the porch on the west side of the house, which was located about 3 miles west of the pump station, when he noticed a "big ball of smoke." He said the smoke then disappeared and later reappeared as a light brown haze. He reported that he did not "hear any noise or explosion." He also said he did not see the airplane fly over the house that particular day. He stated that the reconnaissance airplane usually came over the pump station from west to east, but that this particular day he did not see the airplane fly overhead. A review of the SCIR "Aircraft Pre-Accident Plan and Hazard Map Instructions" booklet stated that an aircraft will be initially considered "overdue" when it has not completed a required check-in by radio or telephone within the time frame specified in the flight following request. This time frame may be an elapsed period of time such as every 15 minutes for reconnaissance flights, or may be ETA at a destination or reporting point. Dispatchers or persons responsible for flight following are responsible for initiating actions and documenting all actions, contact, conversations and times, as specified by the Pre-Accident Plan. During the fire patrol missions, the aircraft uses two FM frequencies for radio contact with dispatch. The aircraft transmits on 171.700 MHz and receives on 172.425 MHz. According to the operator of the aircraft, had the aircraft encountered some sort of mechanical malfunction, which would have allowed the pilot to make a distress call, they would have utilized the guard frequency as called out in procedures specified in the contract. The operator stated in a memorandum dated September 25, 1997, that the "guard" or emergency frequency is a FM frequency of 168.625 MHz, which is monitored by both the USDA and DOI agencies. He explained that the radios installed in his aircraft transmit at 10 watts output. In order to activate the guard frequency, the pilot or observer need only flip a toggle switch located on the face of the radio which is located directly in front of the observer. The operator said that if the pilot initiated a call on the guard frequency from the position of the crash site, it "would have probably been received by several different agencies." He stated that based on his experience flying, various USFS locations in Winslow, Phoenix, Tucson, Springerville, and Silver City, as well as the Bureau Land Management (BLM) dispatch in Safford, would have heard the transmission. The operator said he found that the San Carlos Indian Reservation Dispatch does not have the capability to monitor the Guard frequency. Review of available records disclosed no evidence of contact between any of these stations and the aircraft on the date of the accident. The Safety Board performed a test fight and was not able to contact San Carlos dispatch on the guard frequency, but was able to communicate on the guard frequency with the USFS in Tucson, Arizona. An on-site inspection of the dispatch communication capabilities at San Carlos revealed that they can only transmit and receive on the FM frequencies 171.700 MHz and 172.425 MHz, and the Unicom frequency of 122.8 MHz. They do not have the capability of utilizing the simplex guard frequency of 168.425 MHz. Additionally, the White River Indian Reservation does not have the capability to monitor the guard frequency without "being notified ahead of time and reprogramming the radio frequency." The operator in his summary stated that there were four possibilities for the accident aircraft to declare an emergency: Guard Frequency on FM, primary forestry frequency, Unicom frequency 122.8 (which San Carlos monitors), and the emergency frequency of 121.5. He said that the pilot was very familiar with the options to make a distress call. PERSONNEL INFORMATION The crew for the mission consisted of a pilot and observer. During the investigation, material and records concerning the crews training and experience were examined from the FAA Airman's Record Center, Safford Aviation, and the DOI Office of Aircraft Services. Occupant seating positions were identified by the Pima County Forensic Science Center, with the pilot in the left front seat and the observer in the right front seat. The pilot was an employee of Safford Aviation and the observer worked for the Bureau of Indian Affairs. The pilot was the director of maintenance for Safford Aviation and had collateral duties as a pilot in the company's 14 CFR Part 135 on-demand air taxi operation, and for the fire patrol contract. Review of FAA airman records disclosed that he held a commercial pilot certificate, with airplane ratings for single engine land, multiengine land, and instruments. His most recent second-class medical certificate was issued on January 6, 1997, without limitations. The pilot's personal flight records were not recovered and were believed by family members to have been on the aircraft. According to all sources of information, the pilot had accrued a total flight time of about 1,610 hours, with 795 in multiengine aircraft, and 110 hours in the Beech 95-B55. His most recent check rides in accordance with the provisions of 14 CFR 135 were completed on April 8, 1997, in a Aero Commander 500 aircraft. Additionally, on May 6, 1997, the pilot completed an Interagency Pilot Evaluation/Qualifications Check in the Aero Commander aircraft. A line check in accordance with 14 CFR 135.299 was completed in the accident aircraft on January 12, 1997. The chief pilot of Safford Aviation stated that he gave the pilot a route/line check over the fire patrol route flown on the accident flight in September 1996. The line check included the altitudes and course lines to be flown. The chief pilot also stated that the pilot and the observer had been paired together before on many fire patrol missions. The pilot had also been given several orientation flights on actual reconnaissance flights with the chief pilot acting as pilot-in-command and the observer acting as the aerial observer. According to the chief pilot, the observer could direct the pilot to deviate from a patrol track line; however, the pilot had the option of vetoing any altitude or course change for safety reasons. Review of the FAA Airman Record files disclosed that the observer was issued a private pilot certificate with an airplane single engine land rating in April 1978. The last medical certificate of record was a third-class medical dated January 18, 1977. No evidence was found to indicate that the observer had any recent pilot flight experience. AIRCRAFT INFORMATION According to the best records the operator could find, the airplane was acquired by Safford Aviation, (under different management personnel), in February 1985. A review of the maintenance records disclosed that it had accrued a total time in service of 8,566.9 hours. The most recent 100-hour inspection was accomplished on May 24, 1997, 10.9 hours prior to the accident. According to the records review and interviews with the chief pilot, no unresolved maintenance discrepancies existed against the aircraft at departure. The aircraft was equipped with a 40-gallon (37 usable) main tank in each wing leading edge (Beech anti-slosh reservoir system), and a 31-gallon (all usable) auxiliary tank in each wing panel outboard of the landing gear wheel well. Each main tank was equipped with a Beech anti-slosh fuel cell reservoir assembly. The airport fueling records disclosed that the aircraft was last fueled on June 3, 1997. The operator reported that the aircraft departed on the accident flight with full fuel tanks totaling 117 usable gallons of 100 low lead aviation fuel. The airframe was equipped with Micro Aero Dynamics, Inc., vortex generators which were installed on the wings under Supplemental Type Certificate No. SA5789NM. Both engines were overhauled on July 1, 1996, and had accrued a time in service of 208.5 hours since overhaul completion. As of the accident, the total times in service for the engines were 1,490.2 hours for the left and 3,244.1 hours for the right. As noted in the propeller logbooks, the propellers (left S.N. EB-3226A and right S.N. EB-3227A) were installed new on the aircraft on August 25, 1993, under STC SA795CE with an aircraft tach time of 5,828.7. The last entry for both propellers was a 100-hour inspection performed on May 24, 1997. At that time, both propellers indicated a total time since new of 1,163.5 hours. METEOROLOGICAL INFORMATION Weather observations were taken by the SCIR at the Hilltop Look-out site on the day of the accident. This location is about 42 miles southeast of the accident site. At the time of the accident, the station was reporting in part: temperature 77 degrees Fahrenheit; dew point 56 degrees Fahrenheit; and winds southeast at 7-8 knots with high clouds evident. No unusual meteorological phenomena were observed by any Bureau of Indian Affairs observers. WRECKAGE AND IMPACT INFORMATION The accident site is in a narrow horseshoe shaped canyon formed by the Black River drainage at a measured elevation of 5,620 feet msl. The wall on the west side of the river rises steeply from the river to about 6,100 feet. The bank on the east side of the river is characterized by much shallower terrain slope which rises to match the terrain elevations on the other side of the river. The current in the main channel of the river flows from south to north. The area is characterized by an area of both deciduous and evergreen trees on both sides of the river. The wreckage came to rest on a sandbar of rocks located at the apex of a horseshoe bend in the river. The rocks varied in size from small pea size gravel to rocks that were several inches in diameter. The river itself was relatively shallow at this particular point. Several members of the Tribal Police Department waded out into the river identifying parts of the aircraft and did not get wet beyond mid-calf. The coordinates of the aircraft point of rest were measured with a GPS unit at 33 degrees 29.93 minutes north latitude, by 109 degrees 48.82 minutes west longitude. All major aircraft components were located in the immediate area of the ground impact and final resting point of the aircraft. The right wingtip was found just submerged in shallow water, approximately 60 feet from the main wreckage, at the 7 o'clock position to the aircraft's tail. The separated right wing tip component consisted of the most outboard 36 inches of the right wing. The screw holes through which the attaching hardware passes were elongated and torn open in a span wise direction. The right wing tip exhibited an even according deformation spanwise on it's leading edge structure and on it's center panel structure from wing station 191 to 228. There was an area of deformation located on the leading edge of the wing tip located on the inboard 1/3 that was crushed up and aft. There were no appreciable semicircular indentations found on the wingtip. Additionally, no inorganic or organic material transfers were noted on the leading edge. The landing light lense cover and landing light assemblies were not located with the wing tip in the river. Both the upper and lower green navigation light lens covers were intact. Outer portions of the right elevator skin (with no trim tab attached) were found approximately 4 feet from the left side of the tail section, and were not submerged in the water. The trees in the area of the accident site were examined by the Safety Board for residual marks or transfers from the accident aircraft. Two trees were found upstream
The pilot's failure to maintain an adequate airspeed while maneuvering, which led to an inadvertent stall/spin.
Source: NTSB Aviation Accident Database
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