CHI93FA129

The crew had an electrical fault indication as they started the left engine for a night departure. They shut down the left engine to board a maintenance troubleshooter. The mechanic identified a failed part and obtained its replacement. The failure extinguished the airplane's external lights and prevented its accepting external electrical power. A baggage handler from another airline arrived behind the airplane with bags for the flight. The crew prepared to shut down the right engine to accomplish the part replacement and signalled the marshaller to apply external power to maintain light in the passenger cabin. The marshaller was at the external power receptacle on the front right fuselage when the handler walked forward along the right side and into the turning propeller. The baggage handler was on her second day in that capacity and on night shift. She had been an aircraft cleaner on dayshift for an operator whose fleet is all jet. The job change entailed no classroom or practical training.

History of flight

On April 4, 1993, about 2050 central daylight time, an Aerospatiale ATR-42 airplane, N422MQ, operated by Simmons Airlines as American Eagle Flight 4127, while standing at Chicago, Illinois, struck a baggage handler with the right engine propeller. The handler was fatally injured. No injury was reported among the 3 flight crew and 43 passengers. The airplane incurred minor damage. Night, visual meteorological conditions existed at the field. An instrument flight plan had been filed for a scheduled, domestic passenger flight operating under 14 CFR 121.

The aircraft and crew arrived in Chicago about 1935 and parked at spot F12B. The subsequent flight was scheduled to depart the gate at 2013 for South Bend, Indiana. Passengers boarded and the flight crew started engines. The crew selected anticollision lights and navigation lights ON before engine start. The marshaller assisting the crew recalled no detail about the exterior lighting. Shortly after the starting both engines, the left engine was shut down to board late arriving passengers.

On restarting the left engine, the crew obtained a light in the starter handle, a cue for several discrete indicators. The crew found the DC (direct current) services shed light illuminated; their attempts to regain electrical power by reference to the crew checklist were unsuccessful. They radioed for maintenance assistance and signalled the ground handler to apply external electrical power. The captain shut down the left engine for a mechanic to board and troubleshoot.

The mechanic isolated the fault to a DC bus protection control unit (DCBPCU) and radioed for a replacement part. The DCBPCU screens or qualifies DC electrical power before permitting its distribution. The fault impeded DC power distribution and extinguished external lights.

A driver shuttled a second mechanic with the replacement part to the airplane. The mechanic went to the passenger boarding stair at the airplane's left rear to take the part aboard.

An American Airlines' (AAL) baggage handler had been dispatched from that company's baggage transfer point at another concourse to deliver bundles of skis to the Simmons Airlines' airplane. She parked her vehicle behind the airplane, met the second mechanic at the stair and asked if this were airplane 422. The mechanic confirmed it was, and the handler said she had baggage to go aboard. The mechanic told her she had the correct airplane, then continued up the stair with the part.

The shuttle driver watched from the truck as the two talked. When the mechanic went up the stair, the handler walked around the rear of the airplane and forward on the right side.

Standing at the rear of the cabin, the flight attendant heard the service door at the right rear open. She looked to see a woman on the ramp with a bundle partly in the airplane. The woman then withdrew the bundle and closed the door.

At the troubleshooter's request, the flight crew prepared to shut down the right engine to permit the part replacement. They signalled the marshaller, again, to apply external power to support cabin lighting for the passengers. The marshaller attempted to reseat the connection of a ground power unit at the right side of the forward fuselage.

A passenger in the cabin front looked out the right side windows and saw a woman beside the airplane. After looking to the rear for a moment, she stepped toward the airplane, then turned right and continued forward into the turning propeller.

The marshaller heard an impact and saw the baggage handler prone between the right engine nacelle and fuselage. The bundled skis were in front of the propeller. No flashlight was found, nor did anyone remark seeing one.

Personnel information

The captain held an airline transport pilot certificate with ratings for Shorts 360 and ATR-42/72 aircraft. His flight experience was 9098 hours, with 1153 hours in model. His first class medical certificate was issued October 30, 1992. He completed a proficiency check in model March 27, 1993.

The first officer held an airline transport certificate with rating for ATR-42/72 aircraft. His flight experience was 4859 hours, with 1029 in model. His first class medical certificate was issued September 19, 1993. He completed a proficiency check in model August 28, 1992.

Both pilots are domiciled at the Chicago base. This was to be their third flight on the first day of a 3-day trip.

The baggage handler was a Filipino immigrant, employed by AAL since December 1989. Work associates described her English language facility as good. After a year as a building cleaner, she trained 3 weeks and began as a cabin cleaner in ramp services division, working inside jet airplanes on day shift. Her job title was fleet service clerk. She attended 2 weeks training in October 1992 and returned to the same job. She bid for the new assignment. The day before the accident was her first on night shift and in the capacity of baggage handler. As the "hot baggage runner," her task was to transfer late arriving or outsized bags from the AAL baggage transfer point to connecting American Eagle flights on the ramp.

Aircraft information

Cabin emergency lighting is powered by the DC standby bus with independent battery backup. The emergency lights activate automatically when armed and both main buses are lost or an undervoltage occurs.

Anticollision lights (red rotating beacons) are located on the tail and belly of the airplane. Navigation lights are located on wingtips and tail. Selectable lights on either side of the forward fuselage aim to the engine intakes and wings for the crew's detection of ice in flight. There is no independent battery backup for external lighting.

The lower anticollision beacon had been listed as inoperative before flight and the repair deferred in accordance with the operator's FAA-approved minimum equipment list.

The airplane has an external communication jack for ground personnel with headset and microphone to speak with the cockpit. There is a port behind and below the left pilot seat to pass documents or through which shouted conversation can be exchanged.

The right propeller brake may be used to arrest propeller rotation while the engine is running. A windmilling propeller assists engine cooling.

Baggage is carried in the main cargo area ahead of the passenger cabin; direct access is through the cargo door, forward of the wing on the fuselage left side. A smaller cargo area behind the cabin and galley is indirectly accessible through the service door at the right rear. There is no storage access on the right side, forward of the service door.

The external electrical power receptacle is on the forward fuselage, right side.

The orientation of the blades as the right propeller windmills is full feather, or chords directed forward.

Meteorological information

Weather observed on the field at 2050 CDT was 15 miles visibility below scattered clouds at 4000 feet and an overcast at 25,000 feet. Surface temperature was 33 degrees Fahrenheit. Winds were from 030 degrees at 6 knots, a tailwind to the parked airplane.

Communications

Before engine start, the crew listened to the automated terminal information service for local weather and airport information, and contacted clearance delivery for IFR clearance.

The crew and ramp personnel communicated with hand signals. The flight crew had radio contact with the company's local base, and ramp personnel had hand-held radios to maintenance control.

Aerodrome information

Spot F12B was one of 6 parking spots arrayed by the operator off gates 12 and 14 at the end of F-concourse. The concourse is aligned north and south. The ramp is illuminated by stadium-type lights on poles above the concourse roof. Airfield operations personnel responding to the accident observed the lights on.

Flight recorders

A cockpit