Prospect Heights, IL, USA
N720RA
GATES LEARJET CORP. 35A
The flight was scheduled to pick up cargo at the destination airport and then deliver it to another location. During the descent and 14 minutes before the accident, the airplane encountered a layer of moderate rime ice. The captain, who was the pilot flying, and the first officer, who was the monitoring pilot, made multiple statements which were consistent with their awareness and presence of airframe icing. After obtaining visual flight rules conditions, the flight crew canceled the instrument flight rules clearance and continued with a right, circling approach to the runway. While turning into the base leg of the traffic pattern, and 45 seconds prior to the accident, the captain called for full flaps and the engine power levers were adjusted several times between 50 and 95 percent. In addition, the captain inquired about the autopilot and fuel balance. In response, the first officer stated that he did not think that the spoilerons were working. Shortly thereafter, the first officer gave the command to add full engine power and the airplane impacted terrain. There was no evidence of flight crew impairment or fatigue in the final 30 minutes of the flight. The cockpit voice recorder showed multiple instances during the flight in which the airplane was below 10,000 feet mean sea level that the crew was engaged in discussions that were not consistent with a sterile cockpit environment, for example a lengthy discussion about Class B airspeeds, which may have led to a relaxed and casual cockpit atmosphere. In addition, the flight crew appears to have conducted checklists in a generally informal manner. As the flight was conducted by a Part 135 operator, it would be expected that both pilots were versed with the importance of sterile cockpit rules and the importance of adhering to procedures, including demonstrating checklist discipline. For approximately the last 24 seconds of flight, both pilots were likely focusing their attention on activities to identify and understand the reason for the airplane's roll handling difficulties, as noted by the captain's comment related to the fuel balance. These events, culminating in the first officer's urgent command to add full power, suggested that neither pilot detected the airplane's decaying energy state before it reached a critical level for the conditions it encountered. Light bulb filament examination revealed that aileron augmentation system and stall warning lights illuminated in the cockpit. No mechanical anomalies were found to substantiate a failure in the aileron augmentation system. No additional mechanical or system anomalies were noted with the airplane. A performance study, limited by available data, could not confirm the airplane's movements relative to an aileron augmentation system or spoileron problem. The level of airframe icing and its possible effect on the airplane at the time of the accident could not be determined.
HISTORY OF FLIGHT On January 5, 2010, at 1327 central standard time, a Gates Learjet Corp. 35A, N720RA, operated as Royal Air Freight flight 988 (RAX 988), was destroyed when it impacted water and terrain while maneuvering to final approach to runway 34 at Chicago Executive Airport (PWK), Prospect Heights, Illinois. The captain and first officer sustained fatal injuries. The airplane was owned and operated by Royal Air Freight, Inc., Waterford, Michigan. Visual meteorological conditions prevailed at the time of the accident and an instrument flight rules flight plan was filed for the 14 Code of Federal Regulations Part 91 positioning flight. The flight departed Oakland County International Airport (PTK), Pontiac, Michigan, at 1235. According to the operator, the accident flight was scheduled to pick up cargo at PWK and then transport the cargo to Georgia. The accident flight was the first flight for the flight crew that day. The flight crew reported for duty about 1200. The airplane departed PTK at 1235, en route to PWK. During the takeoff, climb, and en route portions of the flight, no abnormalities were reported by the crew to air traffic control (ATC) nor were any recorded by the cockpit voice recorder (CVR). Review of the CVR transcript revealed that the recording began at 1300:03 while the airplane was en route. At 1306:28, the first officer reported to Chicago air route traffic control center (ARTCC) that their altitude was at flight level two zero zero (20,000 feet mean sea level). The controller then instructed the flight crew to be at 4,000 feet, 35 miles northeast of the Northbrook VOR. At 1308:05, the crew obtained the current automatic terminal information service (ATIS) weather information Quebec for PWK. At 1311:00, the captain stated that he had all the airplane anti-ice systems activated, and a discussion took place involving captain's previous experience flying over the "lake." At 1312:34, the captain stated that the "cabin sucks." Digital electronic engine control (DEEC) data indicated that the engines' low pressure spool speed (N1) was approximately 30 to 50 percent from 1312:18 to 1314:18. At 1314:02, the center controller cleared the flight crew direct to the Northbrook VOR and the first officer acknowledged the clearance. At 1314:25, the captain stated, "yeah, there's ice out there." Seven seconds later, the controller cleared the flight crew to descend and maintain 3,000 feet and contact Chicago approach control, and the first officer acknowledged the clearance. At 1314:58, the first officer stated, "there's ice(ing)," and the captain replied he was glad he had all the airplane anti-ice activated before the descent. The captain stated they were picking up moderate rime ice and the first officer reported the ice conditions to the Chicago approach controller. At 1316:23, the first officer stated, "(look at the) (expletive) tips." Approximately 50 seconds later, the approach controller cleared the flight crew to 2,000 feet and at 1317:37 the first officer reported they broke out of the clouds at 2,600 feet. At 1318:38, the captain stated that he was turning off the anti-ice system and the first officer stated, "don't need it anymore." Between 1311 and 1318 (the time anti-ice system ON as per CVR comments), engine N1 speeds fluctuated between 30 and 80 percent. For approximately the next two and half minutes, the flight crew had a discussion related to airspeeds within the Class B airspace. At 1321:06, the captain stated, "we'll go like one twenty eight on the speed." At 1323:03, the approach controller reported PWK was at their 10 o'clock position and 12 miles, and the first officer reported the airport was in sight. The controller then cleared the flight crew for a visual approach to runway 16 and to contact the PWK air traffic controller tower (ATCT). After contacting ATCT, the flight crew was cleared for a right traffic circling approach to runway 34, and they canceled instrument flight rules (IFR). At 1324:18, the captain called for flaps at 8 degrees and turned the yaw damper off at 1325:02. The flight crew discussed the winds were reported at 310 degrees at 9 knots. At 1325:49, the flight crew was cleared to land and the first officer acknowledged the transmission. Four seconds later, the captain called for the landing gear to be extended. The crew then briefed portions of the before landing checklist and at 1326:27, the captain called for flaps at 20 degrees. At 1327:02, the captain called for full flaps (40 degrees) and the first officer responded, "plus twenty." Post-accident performance studies indicated that the airplane's bank angle increased, and the true airspeed decreased. At 1327:10, one of the two crew members stated, "what the # going on up here." The captain stated, "that was # weird." At 1327:18, the first officer stated, "advance the power," and the sound of laughter followed. Post-accident performance studies indicated that the airplane's true airspeed and N1 increased. At 1327:21, the captain inquired whether the autopilot was off and nine seconds later, one of the crew members stated, "I don't like this at all...what the # is going on." At 1327:34, the captain asked the first officer to check the balance on the fuel, and the first officer responded, "looks good. I don't think that spoileron thing is working for some reason." Post-accident performance studies indicated that the airplane's N1 and true airspeed decreased, and bank angle increased to greater than 50 degrees. The sound of 2 "clicks" was then heard at 1327:41.8 and 1327:42.5, respectively. At 1327:42.7, the first officer stated, "add full power, add full power." The CVR recording ended at 1327:48.5. A witness, who was located at the PWK airport, observed the airplane on a right base leg to runway 34. The witness reported the airplane started to turn to final approach and the bank angle "got very steep, very fast [sic] until the aircraft which seemed to snap roll into a stall and then immediately into a nose dive..." Another witness (a pilot familiar with PWK) who was riding in a vehicle, reported he first observed the airplane on a right downwind for runway 34. He reported, "The aircraft appeared to make a normal downwind to base turn. However, on the base to final turn, the airplane seemed to be slightly uncoordinated with the right wing down, slightly nose low, and the empennage skidding outside of the turn." He then lost sight of the airplane behind buildings and trees. PERSONNEL INFORMATION The director of operations (DO) for Royal Air Freight provided personnel records, training records, and duty and flight time records for the captain and first officer. The information in this section was extracted from that data and Federal Aviation Administration (FAA) records. Captain The captain held an airline transport pilot certificate with an airplane multiengine land rating, and type ratings for Learjets and the Cessna Citation 500 series airplanes. The certificate listed commercial pilot privileges for single engine land airplanes. He was hired by the operator in September of 2003 as second in command (SIC) in Learjet airplanes. In June of 2005, he received transition training to act as pilot-in-command (PIC) in EMB-110 airplanes. On July 2, 2009, he completed Part 135 proficiency and line checks to act as PIC in Learjet airplanes. The captain held a first class airman medical certificate dated April 21, 2009, with no restrictions. On his most recent medical certificate application, the captain listed 7,100 flight hours with 300 hours accumulated within the previous 6 months. Information provided by the operator indicated that the captain had accumulated about 3,000 hours in Learjet airplanes, including 400 hours as PIC. The captain's pilot logbook was not available for review. According to FAA and operator records, the captain had accumulated the following flight time prior to the accident: 7,100 total flight hours, 3,000 hours in all Learjet model airplanes, 168 hours in Learjet model 35A airplanes in the preceding 4 months, 241 hours in the last 90 days, and 73 hours in the last 30 days. The accident flight was the PIC's first flight on January 5th. Operator duty time records indicated that the captain had not been on duty since December 23, 2009. First Officer The first officer held a commercial pilot certificate with single and multiengine land airplane ratings, and a SIC rating for Learjets. He was hired by the operator in February 2005 as a SIC in EMB-110 airplanes. In May of 2006, he received transition training to act as SIC in Learjet airplanes. On June 29, 2009, he completed a recurrent competency/proficiency check for Part 135 SIC Learjet operations. The first officer held a first class airman medical certificate dated April 1, 2009. The medical certificate listed the limitation of available eyeglasses for near vision. On his most recent medical certificate application, he listed 6,700 flight hours with 400 hours accumulated within the previous 6 months. Information provided by the operator indicated that the first officer had accumulated about 3,000 hours in Learjet airplanes as SIC. The first officer's pilot logbook was not available for review. According to FAA and operator records, the first officer had accumulated the following flight time prior to the accident: 7,000 total flight hours, 3,000 hours in all Learjet model airplanes, 126 hours in Learjet model 35A airplanes in the preceding 4 months, 210 hours in the last 90 days, and 62 hours in the last 30 days. The accident flight was the first officer's first flight on January 5th. Operator duty time records indicated that he had not been on duty since December 23, 2009. Flight Crew 72-Hour History Family members for the flight crew reported that both pilots were off over the year-end holiday season and conducted routine tasks around their respective homes. No abnormal routines or health issues were reported. AIRCRAFT INFORMATION The airplane was a 1977 Gates Learjet Corp., model 35A, serial number 156. It was certified under type certificate A10CE as a transport category airplane and initially issued a standard airworthiness certificate on December 12, 1977. The accident airplane was equipped with two Honeywell (Garrett) TFE731-2C-2B turbofan engines, serial numbers P74675 (left) and P74266 (right). The operator purchased the accident airplane on September 25, 2009. The airplane's registration number was subsequently changed from N35WE to N720RA and added to the operator's FAA Part 135 operating certificate. Phase-A / 300-Hour inspections were completed after the change in ownership. In addition, lower cabin structure/fuselage and aft pressure bulkhead inspections were completed. The thrust reversers were deactivated. The airplane was maintained under the manufacturer's prescribed maintenance schedule and current FAA regulations. At the conclusion of the flights the day prior to the accident, the airframe and engine times were recorded as: 15,827.2 hours total airframe time, 13,384.8 hours left engine total time (12,074 cycles), and 15,172.5 hours right engine total time (13,883 cycles). Airplane flight records provided by the operator indicated that the accident airplane was flown 2.6 hours the day prior to the accident (January 4th), which included 3 flight legs. The first originated at 1942 from PTK, and proceeded to Mansfield Lahm Regional Airport (MFD), Mansfield, Ohio. The second leg was from MFD to Columbia Regional Airport (COU), Columbia, Missouri. The final leg was from COU to PTK. It landed at PTK about 0003 on January 5th. There were no discrepancies noted on the daily record sheets within 30 days of the accident. Weight and Balance The operator provided the most recent aircraft weight record which was performed on October 30, 2009. Weight and balance calculations performed using a 6,000 pound fuel load and pilot weights as listed on their most recent airman medical certificates placed the airplane takeoff weight and center of gravity at 16,170 pounds and 385.5 inches respectively. According to the flight envelope contained in the FAA approved Airplane Flight Manual (AFM), provided by the airplane manufacturer, these calculated weights were within the takeoff loading limits for the airplane. Assuming a fuel burn of 1,100 pounds per hour, the calculated landing weight and center of gravity for the 53 minute flight were 15,195 pounds and 384.5 inches respectively. These calculated weights were within the required loading limits specified by the landing flight envelope contained in the AFM. Flap System According to the Airplane Maintenance Manual (AMM) for the Learjet 35, the flap system is electrically controlled (flap switch on the center pedestal), hydraulically operated, provides lift to the wing when partially extended, and increases drag to reduce speed when fully extended. Maximum flap extension is 40 degrees (plus 5 degrees/ minus 0 degrees) down, and flaps should travel from maximum up to maximum down in 6 seconds or less. When the flaps are extended below 25 degrees, the spoilers (in the augmentation mode) work independently to assist the ailerons. Spoiler System The spoilers, located on the upper surface of the wing forward of the flaps, when hydraulically actuated, will hinge up at a specific angle. The spoilers are used either symmetrically as speed brakes or asymmetrically as augmentation to the ailerons for improved lateral control. The spoilers are controlled manually by a switch on the cockpit center pedestal. Spoilers are also controlled automatically through a computer-amplifier during aileron augmentation mode (spoileron mode). The spoilers augment the aileron system when flaps are extended below 25 degrees. During the augmentation mode the spoilers work independently and are controlled by an aileron monitoring system. Adjustable switches, adjacent to the limit switches shut down aileron augmentation in the event of failure. Two other switches, adjacent to the limit switches, actuate the spoiler warning light when the spoilers are not down and locked. Two 13 degree limit switches, one adjacent to each flap sector, cause the spoiler warning light to flash when the flaps are extended below 13 degrees with the Spoiler Switch set to EXT (extend). Whenever the spoiler switch is set to RET (retract), the spoilers will automatically engage to augment the ailerons when the flaps are extended beyond 25 degrees. The spoiler computer-amplifier monitors aileron movement during aileron augmentation. As the ailerons move, the computer-amplifier actuates the spoiler control valve and the spoiler servo valves. As one aileron moves up, the servo valves are actuated to the applicable position and the spoiler on the same wing as the raised aileron extends while the opposite spoiler remains streamlined. The spoiler will rise at a 1 to 1 ratio with the aileron through 14.5 degrees. A limit switch adjacent to each spoiler actuator limits spoiler extension to 16 degrees (plus 1 degree, minus 0 degrees) during aileron augmentation. A monitor circuit automatically disengages the augmentation system, illuminates the amber AUG AIL light on the, and retracts the spoilers if a system malfunction occurs. Depressing the SPOILERON RESET switch will restore system operation if the malfunction has cleared itself. The augmentation mode disengages automatically when flaps are retracted above 25 degrees or is overridden by the spoiler switch. Normal spoiler extension and retraction is accomplished by setting the spoiler switch, on the center pedestal, to EXT or RET. In aileron augmentation mode, the monitor senses both spoiler positions, and also the aileron position, from the right aileron follow-up. The monitor energizes the engage solenoid only if the positions of the spoilers correspond to the aileron position (within 6 degrees), and neither spoiler is raised above 15 degrees. Any fault which causes the spoilers to exceed 15 degrees, or not to track the ailerons, results in retraction and illumination of the AUG AIL light. According to Learjet "this will result in a noticeable but manageable reduction in roll authority. In other words, it will take greater control
A loss of control for undetermined reasons.
Source: NTSB Aviation Accident Database
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