N831BC

HISTORY OF FLIGHTOn December 2, 2013, at 2010 Atlantic standard time, a Fairchild SA227-AC, N831BC, operating as IBC Airways flight 405 ("Chasqui 405"), was destroyed during a rapid descent and subsequent inflight breakup near La Alianza, Puerto Rico. The captain and the first officer were fatally injured. Night visual meteorological conditions prevailed. The international cargo flight was operating on an instrument flight rules flight plan between Las Americas International Airport (MDSD), Santo Domingo, Dominican Republic, and San Juan International Airport (TJSJ), San Juan, Puerto Rico, under the provisions of 14 Code of Federal Regulations Part 135.

According to operator records, the accident flight occurred during the return leg of a round trip between TJSJ and MDSD. Prior to the outbound flight, "normal dispatch requirements were met," and the airplane took on fuel at TJSJ for both legs. The airplane departed MDSD on the accident flight at 1936.

A review of radio transmission transcripts indicated that the crew first contacted the San Juan Combined En route Approach Control (CERAP) facility at 1948, 13 nautical miles west of "MELLA" intersection at 11,000 feet. At 2001, the crew was told to descend to 7,000 feet at "pilot's discretion," and at 2007, the crew was advised to change frequency to the next CERAP sector controller. The crew subsequently contacted the next controller, "leaving one one thousand, descending to seven thousand." The controller then advised the crew to maintain 3,000 feet, expect the ILS (instrument landing system) approach, proceed direct to the "TNNER" fix, and that information "Tango" was in effect. After a crewmember read back the information at 2007:46, there were no further transmissions from the airplane. At 2011:52, the controller advised that radar contact was lost.

According to a Federal Aviation Administration (FAA) inspector interview (the inspector conducted the interview in Spanish and translated it into English), a witness stated that he heard some engine noise, and when he looked outside, he saw the airplane with the right wing down, "turning in a spiral form." He also noticed a red light "spinning." After that, he heard an "impact noise" and 5 seconds later, "another solid impact noise."

Radar data revealed that after crossing MELLA, the airplane proceeded toward TJSJ along a heading of about 085 degrees true, crossing the west coast of Puerto Rico just south of the town of Stella. The airplane maintained 11,000 feet until 2007, and had descended to 8,300 feet by 2010:08. The radar track then indicated a 20-degree turn to the left, and a descent to 7,300 feet by 2010:13. The radar track subsequently indicated about a 45-degree turn to the right, and a descent to 5,500 feet by 2010:18. There were no additional verifiable altitude positions.

Descent calculations between 2010:08 and 2010:13 indicated a rate of descent of about 12,000 feet per minute (fpm), and between 2010:13 and 2010:18, over 21,000 fpm. Groundspeed calculations indicated a fairly constant average of about 260 knots (provided in 10-knot increments) until the airplane initiated a descent. The last two calculations, 1 minute apart and just prior to the rapid descent, were 280 and 290 knots. PERSONNEL INFORMATIONThe captain, age 35, held a commercial certificate with airplane single-engine land and sea, multiengine land and sea, and instrument-airplane ratings. He also held an airplane single engine flight instructor certificate. His latest FAA first class medical certificate was dated April 16, 2013. According to company records, the captain was assigned a captain's position on June 5, 2013, after completing his FAA proficiency checkride on June 3, 2013, and his line checkride on June 5, 2013.

Company records also indicated that as of November 30, 2013, the captain had 1,740 total flight hours, 686 hours in type, 239 hours as pilot-in-command, and 121 hours in the previous 90 days. Night flight hours could not be ascertained.

The first officer, age 28, held a commercial pilot certificate, with airplane single- engine land, multiengine land, and instrument-airplane ratings. His latest FAA first class medical certificate was dated September 9, 2013. At the time, he indicated 1,850 hours of flight time. The first officer was a relatively recent hire; according to company records, he was assigned a first officer position on October 3, 2013 after completing his FAA proficiency checkride on October 2, 2013.

Company records also indicated that as of November 30, 2013, the first officer had 1,954 total flight hours, 92 hours in type, and 92 hours in the previous 90 days. Night flight hours could not be ascertained.

According the company Director of Operations (DO), after arrival in Santo Domingo, the crew would typically have been transported to a local hotel where they would have spent the next 10 hours at rest, typically arriving at the hotel at 0800 and then being picked up at 1800 for transport back to the airport for the flight back to San Juan. "The day was typically spent, resting, eating, lounging by the pool and/or taking a nap; each pilot had their own agenda."

The DO also noted that the company's standard operating procedure was for the non-flying pilot to be responsible for all radio communications. However, it would not necessarily always be the case.

The DO, who had flown with both pilots previously, listened to the radio transmissions recorded by the FAA and recognized the first officer's voice. AIRCRAFT INFORMATIONDescription

Airframe

An Airworthiness Group Chairman's Factual Report is located in the public docket for this accident, including airplane structural diagrams in Attachment 1. From the report, the following airframe description is provided:

The airplane was an all metal, twin engine, propeller driven, low wing, pressurized airplane originally equipped to carry 19 passengers. It had a cruciform tail and retractable tricycle landing gear. The airplane was powered by two turboprop engines and was configured to only carry cargo at the time of the accident.

The fuselage was a semi-monocoque structure composed primarily of aluminum alloy frames, skins, stringers, and bulkheads. The fuselage had three major sections that joined together at production splices. The forebody structure included the cockpit, the mid-section structure included the entry door, emergency exits, passenger windows, cargo door and wing attach points. The aftbody structure included the attach points for the vertical stabilizer. The fuselage could be pressurized between the forward pressure bulkhead and the aft pressure bulkhead.

The wing was attached to the lower portion of the fuselage at four points, two on the main spar and two on the rear spar. The wing was a one-piece design with continuous main and rear spars, integral fuel tanks and removable flaps and ailerons. The spars were built-up I-beam structures constructed of aluminum alloy with titanium alloy and steel alloy reinforcements on the upper and lower spar caps. The height of both the main and rear spars decreased where they passed under the fuselage. The main spar transitioned from about 13 inches tall to about 9 inches tall and the rear spar transitioned from about 10 inches tall to about 9 inches tall. Five-foot wing extensions were attached to the outboard end of each wing to increase the span to 57 feet.

The airplane also included conventional horizontal and vertical stabilizers composed primarily of aluminum alloy components. The vertical stabilizer was a cantilever design with two spars attached to bulkheads in the aft fuselage. A cable-driven rudder and trim tab were attached to the aft spar of the vertical stabilizer. The horizontal stabilizers were of cantilever design fastened together at the fuselage centerline and attached to the vertical stabilizer with a trunnion bolt. The stabilizer could pivot around the trunnion bolt, changing the angle of incidence of the stabilizer and providing pitch trim for the airplane.

All-aluminum cable-driven elevators were attached to the horizontal stabilizers and fastened together at the center splice plate hinge point. The pitch trim was controlled electrically by switches on the control yokes that actuated two motor-operated jackscrews mounted to the top of the fuselage.

The ailerons, elevators, and rudder were manually controlled from either the pilot or copilot station in the cockpit by a conventional yoke and rudder pedals. Aileron control cables, 1/8 inch in diameter, interconnected the yokes and ran through several pulleys aft under the floor to an aileron drum in the center wing area. The aileron drum was connected to a series of push-pull tubes that ran along the aft side of the rear spar on each wing to bellcranks mounted near the aileron inboard hinges. Push-pull tubes connected the ailerons to the bellcranks for aileron control.

Elevator control cables, 1/8 inch in diameter, ran from the elevator walking beam immediately aft of the columns through several pulleys aft under the floor to the elevator quadrant in the vertical stabilizer. Push-pull tubes connected the elevators to the quadrant for elevator control. Rudder cables, 1/8 inch in diameter, ran through several pulleys aft under the floor to the rudder bellcrank in the aft fuselage. A rudder bellcrank drove the rudder torque tube for rudder control. Aileron and rudder trim were manually set via control wheels on the center pedestal in the cockpit. The aileron and rudder trim cables, 1/16 inch in diameter, ran through several pulleys to their respective tabs. The flaps were electrically controlled and hydraulically actuated.

Fuel System

According to the SA227 Maintenance Manuel, the fuel system had a usable capacity of 648 U.S. gallons. Fuel was contained in integral left and right wing fuel tanks.

Each engine was supplied fuel by an independent system that included the tanks, boost pumps and check valves. An interconnect...