Accidents: February 2020

 - February 3, 2020, 5:26 AM

Preliminary Reports

Runway Excursion Closes Liverpool Airport

Bombardier BD-700-1A11 Global 6000, December 11, 2019, Liverpool, United Kingdom—The Liverpool John Lennon Airport was closed for more than 17 hours after a landing corporate jet veered off the runway and became mired in mud less than 60 meters (200 feet) from the pavement. A minimum buffer of 75 meters is required to continue operations. 

A specialist removal team eventually dug a track back to the runway, which was subsequently inspected for damage. No one was injured, but more than 9,000 passengers were delayed, rebooked, or transferred to flights out of Manchester.

No Survivors in Hawaii Air Tour Crash

Eurocopter AS350B2, December 26, 2019, Lihue, Kauai, Hawaii—Six tourists and the pilot were killed after their helicopter struck a ridgeline during an air tour of the famed Na Pali coast, an area of extremely rugged terrain and widely varying microclimates. The flight was reported missing at 6 p.m., about 40 minutes after its expected return time. Poor visibility and high winds hampered initial search efforts; the wreckage was eventually located around 9:30 the following morning in a remote area of steep terrain. Six bodies were recovered before deteriorating weather forced suspension of the search. The last victim was found the following day.

In a press release issued on December 31, the NTSB reported that the aircraft fell about 100 feet after striking the ridge at an altitude of approximately 2,900 feet. The passengers included a mother and 13-year-old daughter from Wisconsin and a Swiss couple with their two daughters, aged 10 and 13. The tour was being flown by the operator’s 69-year-old chief pilot. The NTSB’s preliminary report had not been published at press time.

Five Deaths in Louisiana Cheyenne Accident

Piper PA-31T, December 28, 2019, Lafayette, Louisiana—A Piper Cheyenne II crashed barely one minute after taking off from the Lafayette (Louisiana) Regional Airport, killing the pilot and four of the five passengers. The surviving passenger was hospitalized with injuries described in press accounts as including burns over 75 percent of his body and a dislocated shoulder. A motorist whose car was struck by the aircraft also suffered serious injuries, and two employees of a post office at the accident site were struck by shards of flying glass.

The airplane took off from Runway 22L at 9:20 a.m. on an instrument flight plan to Atlanta’s Dekalb-Peachtree Airport. ADS-B data provided by the FAA showed that it climbed out at rates between 1,000 and 1,900 fpm while making a slight right turn toward its assigned heading of 240 degrees. Thirteen seconds after takeoff it began rolling back toward wings level, then continued rolling left. It reached its peak altitude of 885 above ground level in a 35-degree left bank and continued rolling left while descending. The last observation showed it descending through 600 feet at 2,000-3,000 feet per minute while banked 70 degrees to the left. The pilot did not respond to a low-altitude warning from the controller.

Local weather at the time included vertical visibility of 200 feet, ground visibility of ¾ mile, five-knot winds from the southeast, and identical temperature and dewpoint of 19 degrees Celsius.

Final Reports

Spurious Torque Alert Misinterpreted by Crew

Pilatus PC-12, January 6, 2016, Savannah, Georgia—The pilots misinterpreted a torque exceedance alert as low torque and then attempted a precautionary landing without following the operating handbook’s troubleshooting procedures, causing substantial damage including a post-crash fire when the airplane struck a ditch while landing in the grass perpendicular to the runway, according to the NTSB. Takeoff performance was normal, but after a positive rate of climb was established, both pilots noted a red crew alerting system (CAS) torque warning. The torque gauge read 5.3 psi, while nominal torque for the day’s conditions was 43.3 psi. With the airplane 200 feet above the ground with 2,700 feet of runway remaining and the landing gear still extended, the pilot flying chose to reduce power and turn left to land in the grass between the runways and the terminal.

Data retrieved from the airplane’s avionics suite showed a sudden spike in indicated torque from 45.0 to 71.0 psi, triggering an engine caution alert. Other engine indications remained normal. Four seconds later the torque reading decreased to 47.3 psi and other engine indications also decreased, consistent with a reduction in power. The NTSB noted that the PC-12’s CAS provides alerts only for excessive torque, and the response to a torque alert specified by its operating handbook is to reduce power, landing “as soon as possible using minimal power” if the alert does not resolve. The stable values recorded for other engine parameters led the Board to conclude that both the torque exceedance warning and low torque indication resulted from equipment errors.

Panel Dimmer Implicated in Fuel Starvation

Airbus Helicopters Deutschland MBB-BK 117 B-2, July 1, 2017, Perryland, Missouri—Dimming the panel lights for a flight at dusk may have prevented a medevac pilot from seeing the low-fuel or master caution lights, according to the NTSB. The pilot, three crew members, and the patient being transported suffered only minor injuries when the helicopter landed hard and rolled over following an emergency autorotation in response to a dual engine stoppage. Investigators subsequently found the switches controlling the fuel transfer pumps in the “off” position. These pumps transfer fuel from the main tanks to the supply tanks that feed the engines directly, and are normally activated before takeoff.  

The aircraft had been fitted with a night-vision-goggle-compatible interior lighting system installed under a supplemental type certificate, which included infrared filters over the instruments and annunciator panel. Subsequent examination found that with the panel lights dimmed, the low-fuel warning and master caution lights could not be seen. The transmitters that activate the low-fuel annunciators also illuminate the master caution light but do not trigger any audible warning tone.

Seventeen minutes into the flight, the helicopter yawed left “with a hard-upward bump.” Engine, generator, and battery discharged warning lights illuminated. The nose pitched up and rolled right and the pilot entered autorotation but had to alter his glide path to avoid power lines and a ditch. The helicopter landed right skid-low and skidded about 100 feet before rolling onto its right side. After evacuating the occupants, the pilot saw fuel streaming from one of the belly drains and shut down the fuel and electrical systems to reduce the risk of fire.

Missed Turn Led to Nature Air Disaster

Cessna 208, December 31, 2017, Punta Islita, Costa Rica—Confirming prior reports, the NTSB found that the flight crew’s failure to make an immediate right turn after takeoff placed the airplane in a narrow valley with no exit, flying toward terrain it could not outclimb. Both pilots and all 10 passengers were killed when the Nature Air Caravan stalled into the ground as the crew attempted to reverse course. Investigators' analysis of surveillance footage suggests that the airplane reached a bank angle of 75 degrees at a groundspeed of about 82 knots, well below the published stall speed for a 60-degree bank. Another company airplane that left 15 minutes earlier made the right turn, departing the valley through a gap in the surrounding hills and arriving without incident at the Juan SantamarĂ­a International Airport in San Jose.

The reasons the crew chose to take off from Runway 03 of the privately-owned airstrip rather than the unobstructed departure over the ocean from Runway 21 remain unclear. Two windsock frames were present at the field but no windsocks were installed at the time. The nearest certified weather station, some 25 miles away, reported winds from 090 degrees at four knots with gusts to 12, but a witness on the scene estimated winds there at 10 to 15 knots. The 3,000-by-30-foot runway does not have parallel taxiways, instead, requiring a back-taxi and use of a turnaround pad for southbound departures.

While the company’s General Operating Manual called for airport-specific training for pilots “operating to or from airports with special characteristics,” it did not list those fields. However, the witness reported having spoken with the pilots of both airplanes before they took off, and that they’d acknowledged the need to turn right and toward the eastern pass when taking off from Runway 03.

Flight Control Failure Traced to Corrosion

Eurocopter EC135T1, February 26, 2019, Owen Roberts International Airport, Grand Cayman, Cayman Islands—Undetected corrosion caused a fracture of the longitudinal axis tie bar in the main rotor actuator assembly, leading to a hard landing that damaged the tail boom, landing gear, and transmission deck. The helicopter had just lifted into a four-foot hover when the pilot felt a vibration in the cyclic followed by “a strong rearwards force, which he was unable to overcome.” He immediately lowered collective, and the helicopter landed hard. The pilot shut down both engines and applied the rotor brake, and the crew evacuated the ship without further incident.

The EC135’s main rotor actuator consists of three parallel hydraulic circuits that deflect the swashplate in the longitudinal, lateral, and collective dimensions via a system of tie rods, forks, and bellcranks. The system does not receive any routine maintenance while installed in the helicopter. Split compression rings of varying thicknesses are used as shims to standardize actuator length so that replacing an actuator mechanism does not require adjusting the swashplate linkages; the gap between the ring segments could allow moisture to enter and pool against the outermost O-ring in precisely the area where the fracture occurred. Metallurgic analysis found pitting corrosion on the surface of the tie bar and intercrystalline corrosion and crack propagation on the fracture surface. High concentrations of sodium and chlorine were also found, consistent with moisture penetration in a highly saline marine environment.

Following the accident, EASA issued Emergency Airworthiness Directive 2019-0087-E requiring a one-time removal and inspection of “a specific group of actuators” and mandating replacement of any tie bars that show evidence of corrosion or have exceeded their authorized time in service.