Incident Overview
On March 2, 2016, at approximately 0800 eastern standard time, a Beech 99A, registration N198WA, operated by Wiggins Airways Inc., experienced severe turbulence while on approach to Knox County Regional Airport (RKD) in Rockland, Maine. The flight, a non-scheduled cargo operation under 14 CFR Part 135, originated from Manchester Airport (MHT) in Manchester, New Hampshire, around 0730. Instrument meteorological conditions (IMC) prevailed, and the flight was operating under an instrument flight rules flight plan.
The pilot reported that during the descent for the instrument landing system approach to RKD, the airplane encountered an area of continuous light to moderate turbulence. At approximately 2,000 feet mean sea level and an airspeed of about 130 knots, the airplane encountered severe turbulence, prompting the pilot to initiate a missed approach. She decided not to attempt another approach to RKD and instead diverted to Bangor International Airport (BGR) in Bangor, Maine. En route to BGR, the airplane continued to experience light to moderate turbulence. After landing and securing the airplane, the pilot documented the severe turbulence encounter in the aircraft logbook.
Aircraft and Pilot Information
The pilot held an airline transport certificate with ratings for airplane single-engine land, multi-engine land, and instrument airplane. She also held a first-class medical certificate issued on March 15, 2016. Her most recent flight review was completed on November 24, 2015. At the time of the incident, the pilot reported 3,600 total flight hours, with 2,784 hours in the accident airplane make and model. She had accumulated 480 hours of flight experience in IMC, of which 295 hours were in the accident airplane make and model.
Weather Conditions
The weather observation at RKD at 0756 recorded wind from 150 degrees at 20 knots, gusting to 30 knots; visibility 4 statute miles in mist; ceiling overcast at 700 feet above ground level; temperature 8 degrees Celsius; dew point 7 degrees Celsius; and altimeter setting 29.43 inches of mercury. A peak wind from 150 degrees at 34 knots was recorded at 0716, with pressure falling rapidly.
The Terminal Aerodrome Forecast for RKD valid at the time predicted wind from the southeast at 22 knots with gusts to 37 knots and the potential for low-level wind shear at 2,000 feet, with wind from 180 degrees at 45 knots. The National Weather Service issued multiple AIRMETs for the region advising of widespread IMC, moderate turbulence, and low-level wind shear. There were no pilot reports or SIGMETs for severe turbulence in the area.
Damage Assessment
Examination of the airplane by a Federal Aviation Administration inspector revealed that both wings exhibited skin deformation, and the fuselage side skins were wrinkled. Further examination by a local repair station revealed substantial damage to the right wing root between the fuselage and nacelle, just aft of the main spar. The right wing root-to-fuselage fillet fairing was also damaged just aft of the main spar. Several other areas on both wings were noted with wrinkled skin.