ERA14FA045

The pilot's failure to maintain control of the airplane following an inflight deployment of the left engine thrust reverser. Contributing to the accident was the flight crew's failure to perform the appropriate emergency procedures, the copilot's lack of qualification and capability to act as a required flight crewmember for the flight, and the inflight deployment of the left engine thrust reverser for reasons that could not be determined through postaccident investigation.

During takeoff to the east over the ocean, after the twin-engine jet climbed straight ahead to about 2,200 ft and 200 knots groundspeed, the copilot requested radar vectors back to the departure airport due to an "engine failure." The controller assigned an altitude and heading, and the copilot replied, "not possible," and requested a 180-degree turn back to the airport, which the controller acknowledged and approved. However, the airplane continued a gradual left turn to the north as it slowed and descended. The copilot subsequently declared a "mayday" and again requested vectors back to the departure airport. During the next 3 minutes, the copilot requested, received, and acknowledged multiple instructions from the controller to turn left to the southwest to return to the airport. However, the airplane continued its slow left turn and descent to the north. The airplane slowed to 140 knots and descended to 900 ft as it flew northbound, parallel to the shoreline, and away from the airport. Eventually, the airplane tracked in the direction of the airport, but it continued to descend and impacted the ocean about 1 mile offshore. According to conversations recorded on the airplane's cockpit voice recorder (CVR), no checklists were called for, offered, or used by either flight crewmember during normal operations (before or during engine start, taxi, and takeoff) or following the announced in-flight emergency. After the "engine failure" was declared to the air traffic controller, the pilot asked the copilot for unspecified "help" because he did not "know what's going on," and he could not identify the emergency or direct the copilot in any way with regard to managing or responding to the emergency. At no time did the copilot identify or verify a specific emergency or malfunction, and he did not provide any guidance or assistance to the pilot. Examination of the recovered wreckage revealed damage to the left engine's thrust reverser components, including separation of the lower blocker door, and the stretched filament of the left engine's thrust reverser "UNLOCK" status light, which indicated that the light bulb was illuminated at the time of the airplane's impact. Such evidence demonstrated that the left engine's thrust reverser became unlocked and deployed (at least partially and possibly fully) in flight. Impact damage precluded testing for electrical, pneumatic, and mechanical continuity of the thrust reverser system, and the reason the left thrust reverser deployed in flight could not be determined. No previous instances of the inflight deployment of a thrust reverser on this make and model airplane have been documented. The airplane's flight manual supplement for the thrust reverser system contained emergency procedures for responding to the inadvertent deployment of a thrust reverser during takeoff. For a deployment occurring above V1 (takeoff safety speed), the procedure included maintaining control of the airplane, placing the thrust reverser rocker switch in the "EMER STOW" position, performing an engine shutdown, and then performing a single-engine landing. Based on the wreckage evidence and data recovered from the left engine's digital electronic engine control (DEEC), the thrust reverser rocker switch was not placed in the "EMER STOW" position, and the left engine was not shut down. The DEEC data showed a reduction in N1 about 100 seconds after takeoff followed by a rise in N1 about 35 seconds later. The data were consistent with the thrust reverser deploying in flight (resulting in the reduction in N1) followed by the inflight separation of the lower blocker door (resulting in the rise in N1 as some direct exhaust flow was restored). Further, the DEEC data revealed full engine power application throughout the flight. Although neither flight crewmember recognized that the problem was an inflight deployment of the left thrust reverser, certification flight test data indicated that the airplane would have been controllable as it was configured on the accident flight. If the crew had applied the "engine failure" emergency procedure (the perceived problem that the copilot reported to the air traffic controller), the airplane would have been more easily controlled and could have been successfully landed. The airplane required two fully-qualified flight crewmembers; however, the copilot was not qualified to act as second-in-command on the airplane, and he provided no meaningful assistance to the pilot in handling the emergency. Further, although the pilot's records indicated considerable experience in similar model airplanes, the pilot's performance during the flight was highly deficient. Based on the CVR transcript, the pilot did not adhere to industry best practices involving the execution of checklists during normal operations, was unprepared to identify and handle the emergency, did not refer to the appropriate procedures checklists to properly configure and control the airplane once a problem was detected, and did not direct the copilot to the appropriate checklists.

Direction General of Civil Aeronautics (DGAC) of Mexico Report On or about November 20, 2013, the DGAC performed an inspection of the operator, Aero JL. The results of the inspection produced multiple documents, which were forwarded to and translated by the FAA in Washington, D.C. The translator prepared a spreadsheet that identified the various categories inspected, the discrepancies noted, and the responses to each discrepancy by Aero JL. According to the report, in the Recurring Training category, the general operations manual under Annual Flight Personnel Recurring Training Program did not "specify included nor authorized personnel." The report did not specify what, if any, recurring training was to be completed by flight personnel, or if the same requirements applied to contract pilots. The airplane was equipped with an L-3/Fairchild FA2100 -1020, 2-hour, solid state cockpit voice recorder (CVR) from which about 2 hours of usable audio, including the entire 6-minute accident flight, were captured. The quality of the recording suggested that the copilot used a headset microphone, and the pilot's voice was captured over an area microphone. Thrust Reverser Control Switch and Indication Panel Examination of the thrust reverser control panel revealed that the rocker switch was intact and depressed on the left, which, according to the manufacturer, was consistent with the "NORM" (normal) position. Examination of the status lights on the thrust reverser indication panel revealed that the filaments of the light bulbs for the left engine's "UNLOCK" status light was stretched, and the filament for the "DEPLOY" light was coiled and intact. For the right engine, the filament for "UNLOCK" was coiled and broken, and for "DEPLOY" it was coiled and intact. Digital Electronic Engine Control (DEEC) Operation and Data Recovery The model DEECs on the airplane included an incident recorder that collected engine and aircraft operational data and recorded it into Non-Volatile Memory (NVM). The recorder provided a record of engine speeds and inter-turbine temperatures, aircraft parameters relating to the engine, and control modes during operation. The DEEC casing was not designed to be crashworthy; therefore, memory data could be damaged or lost for a variety of reasons including, but not limited to, impact and fire damage. The incident recorder collected data into memory for about 85 minutes of the final engine ground and/or flight time while the DEEC was powered. The DEEC recording methodology was that the actual discreet data parameter was not physically recorded to memory. Rather, a digital bit value that corresponded to a data parameter range was recorded to memory whenever a parameter was within a given range. The DEECs from the accident airplane were recovered from the ocean, and their data downloaded successfully at Honeywell, the component manufacturer. The examination of the DEEC data revealed that, during the entire accident flight, both engines were rotating, operating, and responding to power lever inputs. The data for each engine after that time were summarized below. Left Engine DEEC Data Summary About 100 seconds after takeoff, the left engine DEEC data indicated the following within 1-2 seconds: The DEEC computer sensed an N1 error in commanded speed, indicating the engine was slowing below the commanded value. The DEEC computer tripped/changed to manual mode and the N1 began an abrupt decrease, and declined to between 60 percent and 65 percent. Further, the Mach value transitioned below 0.15 and, as a consequence, the calculated weight on wheels transitioned from "in air" to "on ground". The N1 drop/decrease lasted for about 35 seconds. During the N1 decrease, the recorded power lever angle and N2 values remained unchanged. N2 was unchanged throughout the N1 rollback, as well as the rest of the flight. After the 35-second decrease, the recorded N1 values returned to between 80 and 85 percent. Right Engine DEEC Data Summary The DEEC data recovered for the right engine showed that the engine was operating and responding to power lever movements throughout the accident flight. The right engine data did not show any variations in N1 as indicated in the left engine DEEC data. Examination of the DEEC data indicated that, except for a 35-second time period for the left engine, the values recorded for each engine were similar. After the left engine N1 decrease and for the remainder of the recorded data (60 seconds), both engines operated at an N1 of between 85-95 percent and an N2 RPM between 90-101.5 percent. Examination of maintenance records revealed that as of the most recent inspection, all Airworthiness Directives were complied with and up to date. Procedures and Checklists Section III of AFM Supplement, "Aeronca Thrust Reversers," contained the Emergency Procedures for an inadvertent thrust reverser deployment during takeoff. According to the procedures, "an inadvertent thrust reverser deployment during takeoff will be indicated by illumination of the affected thrust reverser UNLOCK and/or DEPLOY lights." The procedures stated that, if this occurred below V1 speed, an aborted takeoff should be performed. The procedures stated that, if this occurred above V1 speed, the flight crew should maintain directional control, reduce the affected engine thrust lever to idle, place the NORM-EMER STOW switch to EMER STOW, and continue the takeoff. The procedures stated that, "If UNLOCK or DEPLOY lights do not go out, Thrust Lever (affected engine) – CUTOFF." The procedures stated that the ENGINE SHUTDOWN IN FLIGHT procedure in the basic AFM should be performed. Section IV of AFM Supplement, "Aeronca Thrust Reversers," contained the "Abnormal Procedures" for an inadvertent thrust reverser deployment in flight. Those procedures also specify that, if the UNLOCK or DEPLOY lights do not go out, the ENGINE SHUTDOWN IN FLIGHT procedure should be performed, followed by the SINGLE-ENGINE LANDING procedure from the basic AFM. Records Reviews Reviews of the airplane manufacturer's records and the NTSB accident and incident database found no previously documented instance of an un-commanded inflight deployment of a thrust reverser on a Learjet 35. Airplane Certification Tests: Flight with One Thrust Reverser Deployed From October 7 to 11, 1977, Gates Learjet performed "In-Flight Unwanted Deployment" testing of the thrust reverser and published a report. The tests were conducted in a variety of airspeed and altitude modes. According to the flight tests conducted by an FAA pilot, Flight Test Condition 22 was at the same airspeed as the accident flight scenario and the controllability of the airplane was "acceptable." A landing was conducted in gusty conditions with a thrust reverser deployed, and according to the report, "Landing with the thrust reverser deployed and the engine shut down is the same as a single engine landing since no parts of the thrust reverser are in the free stream air." According to the airplane manufacturer, in the event of an in-flight emergency, the typical convention was for the pilot flying to fly the airplane and take over communications with ATC. The pilot monitoring should then complete the appropriate checklist, while audibly announcing his actions as they are completed. The pilot flying was to verify these actions prior to completion. Although different flight departments may adopt their own procedures, there was no evidence that any crew coordination actions took place on the accident flight. The Office of the Broward County Medical Examiner, Fort Lauderdale, Florida, performed the autopsy on the copilot. The autopsy revealed the copilot died from multiple blunt force injury. The FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed forensic toxicology on specimens from the copilot. These tests were negative for drugs, alcohol, or carbon m