CHI96IA191

The pilot-in-command reported smelling smoke during descent. Smoke was coming out of the bottom left corner of the first officer's windscreen. The first officer, using the portable halon fire extinguisher, extinguished a 6 to 8 inch flame that had erupted from behind the glareshield. The PIC completed the approach and landing. Examination of the windshield by the manufacturer indicated that the source of the excessive heat that caused the windshield and aircraft materials to smoke and ultimately burn, was determined to be arcing of a damaged low power braided copper lead wire. The examiner reported that, 'It is, however, our opinion that the damage was done to the braid wire during the windshield manufacturing process.' The origin of the fracture of the inboard glass ply was in the bottom center post corner area located near the low power terminal block. The examiner reported that, 'the glass fracture occurred as a result of the intensive heat due to electrical arcing of the severed low power lead wire.'

On June 6, 1996, at 1424 eastern daylight time, a Beech 1900, N81538, operated by Continental Express, Flight 3123, sustained minor damage as a result of an in-flight fire. The 14 CFR 135 commuter airplane had departed Cleveland International Airport, Cleveland, Ohio, en route to Capital City Airport, Lansing, Michigan, and was 15 miles southeast of Lansing when the crew observed smoke and flames coming from behind the copilot's glareshield. The crew put out the fire with a fire extinguisher and landed at their destination with no further incident. There were no injuries to the two crew members or to the 16 passengers. The passengers were deplaned normally. Instrument meteorological conditions prevailed and an instrument flight plan was filed.

The Pilot in Command (PIC) reported that during the descent he and the First Officer smelled smoke or burning plastic. They saw smoke coming out of the gasper fans. When they had reached about 5,000 feet mean sea level (MSL), they saw smoke coming out of the bottom left corner of the First Officer's windscreen. The crew donned their oxygen masks and deployed the passenger oxygen masks. The PIC initiated smoke elimination procedures and declared an emergency. The First Officer, using the portable halon fire extinguisher, extinguished a 6 to 8 inch flame that had erupted from behind the glareshield. The PIC completed the approach and landing and taxied to the gate.

A preliminary examination of the aircraft determined that the heavy smoke residue on the windshield inboard surface came from the anti-ice heating system low power terminal block area. The terminal block was also severely damaged. The inboard glass ply of the windshield was broken. It had a fracture pattern that was contained to a small area in the lower center post. The annunciator panel cover which was adjacent to the windshield terminal block area had signs of burning and melting.

The right-hand windshield, designated Beech part No. 114-384020-2, PPG part No. BA-047-2, S/N 95258H5128, was removed from the aircraft and sent to the manufacturer for a detailed failure analysis. The examination and failure analysis of the windshield was conducted at the PPG Glass Technology Center by Mr. E. Kuppra on June 11, 1996. Personnel present to witness the teardown and analysis was Mr. P. M. Rivera of the Allegheny County Federal Aviation Administration (FAA), Mr. John Ward of Raytheon Aircraft Co., and Mr. Jim Myers of PPG-Aircraft Products.

The manufacturer reported the following results of its examination:

(1) The source of the excessive heat that caused windshield and aircraft materials to smoke and ultimately burn was determined to be arcing of a damaged low power braided copper lead wire. This damaged area of the lead wire was located under the fiberglass edge attachment strap at the inboard surface edge seam area of the inboard glass ply.

(2) It was difficult to determine the exact cause and type of original damage to the lead wire due to the excessive heat and deterioration of the wire at the arcing vicinity. However, it is believed that the lead wire was damaged during the fabrication of the windshield.

(3) The origin of the fracture of the inboard glass ply was in the bottom center post corner area located near the low power terminal block. The fracture origin was on the inboard surface, 0.34 inch from the bottom glass edge and 1.10 inches from the center post glass edge. The origin was in an area of severe erosion of the inboard glass surface that was 0.028 inch deep. The glass fracture occurred as a result of the intensive heat due to electrical arcing of the severed low power lead wire. This caused severe surface damage and the high thermal exposure which reduced or eliminated the compressive pre-stress from tempering. This resulted in a low stress fracture.

The investigation concluded that the source of extreme heat was electrical arcing of the low power lead wire. The origin of the arcing was at, or very near, the inboard surface edge seam of the inboard glass ply. It was difficult to determine the exact cause and severity of the original damage to the wire because of the excessive heat and deterioration of materials. It was, however, in the inspector's view that "the damage was done to the braid wire during the windshield manufacturing process."

The FAA determined that an unsafe condition had been identified in two Beech 1900D's and that was likely to exist or develop in other Beech 1900D airplanes. As a result, the FAA issued a Priority Letter Airworthiness Directive (AD) 96-15-01. The AD required deactivation of windshield heat by pulling and securing "open" both Captain's and First Officer's electrical power/control electrical circuit breakers. A placard was also required to be installed on the instrument panel prohibiting operation in Known Icing Conditions. The AD mandated compliance prior to further flight. (See attached AD)

In response to the FAA AD 96-15-01, the Raytheon Aircraft Corporation issued Communique #43 to all Beech 1900 airline operators. Communique #43 described the windshield replacement program that Raytheon Aircraft was providing for operators of Beech 1900D airliners. (See attached Communique #43)