NTSB Factual Report

HISTORY OF FLIGHT

On July 31, 2009, at 1516 central daylight time, a Raytheon Aircraft Company BE-400A airplane, N679SJ, received minor damage after being struck in the number two engine by at least one bird while on initial takeoff from Sugar Land Municipal Airport (SGR), Houston, Texas. Visual meteorological conditions prevailed at the time of the incident. The flight was being conducted under the provisions of 14 Code of Federal Regulations (CFR) Part 91 with an instrument flight rules (IFR) flight plan. The cross country flight was originating from SGR with Lakefront Airport (NEW), New Orleans, Louisiana, as the final destination.

The pilot stated the airplane was on departure roll approaching 95 knots when one large and two smaller birds were observed flying across the airplane’s flight path from left to right. He described the two smaller birds as "sparrow” sized and the larger bird as a heron about four or five times larger than the smaller birds. The pilots were unable to react before at least one of the birds struck the airplane. The pilot stated the right engine immediately lost all power and they rejected the takeoff. Post-flight examination of the airplane revealed all but one of the right engine fan blades were fractured and the inlet duct had separated from the front of the engine and was hanging from the engine by a bleed air tube.

AIRPLANE INFORMATION

The airplane, a Raytheon Aircraft Company BE-400A model, was powered by two Pratt & Whitney Canada (PWC) JT15D-5 engines. The PWC JT15D-5 engine was a dual-spool turbofan that featured a one-stage fan, a one-stage axial flow booster, a one- stage centrifugal flow high pressure compressor (HPC), a reverse flow annular combustor, a one-stage high pressure turbine that drove the HPC, and a two-stage low pressure turbine that drove the fan and booster stages.

TESTS AND RESEARCH

A bird’s head and wing were recovered from the runway. In addition, a U.S. Department of Agriculture Wildlife Service’s biologist later recovered bird remains from the inlet duct. The bird’s wing and the bird remains were individually submitted to the Smithsonian Institute Museum of Natural History Feather Identification Laboratory. Each sample and a photo of the recovered bird head identified the bird as a juvenile yellow-crowned night heron. According to the Smithsonian Institute Feather Identification Laboratory, juvenile yellow-crowned night herons can weigh 1 ½ to 2 pounds.

The airplane’s right engine, serial number PCE-JA0103, was removed from the airplane and sent to the Pratt & Whitney Engine Services engine repair facility for examination under the supervision of a NTSB investigator. The examination revealed that although all but one of the fan blades were fractured adjacent to the root platform, there were no penetrations through the fan case. The spinner was missing from the engine, but scoring marks the approximate size and shape of the spinner were observed on the inside of the inlet duct. The metallurgical examination of the shaft, which secures the spinner, showed the fracture to be rotational bending type of fracture. The metallurgical examination of the fan blades identified several blades that had traces of the alloy used in the spinner on the surface of the blades.

According to the JT15D-5 engine’s type certificate data sheet (TCDS), the engine was certified to 14 CFR Part 33 and Advisory Circular (AC) 33-1B requirements. Certification requirements in place at the time of certification stated the engine must be able to ingest a 4-pound bird, if it could enter the inlet, at climb speed with the engine at take off power. The requirements stated the engine is acceptable if it ingested the bird and “demonstrated freedom from explosion, disintegration, or uncontrollable fire.” AC-33-1B further stated that it would be acceptable if the engine required shutdown.

According to PWC Engineering Report No. 1105, “JT14D-5 Certification 4 Pound Ingestion Test” the JT15D-15 engine was tested to demonstrate the ability of the JT15D-15 engine to meet the certification requirements established for large bird ingestion. According to the report, a four pound snow goose was shot at a velocity of 505 feet per second (299.2 knots) into a JT15D-5 engine that was operating at maximum cruise power. The report stated the snow goose struck the fan rotor at the outer diameter of the nose cone and the inner ends of the fan blades. All of the fan blades remained intact, but 5 of the 47 blades were noticeably bent and 13 other fan blades had the leading edge tip corner bent. The nose cone had several indentations and all 38 of the fan core stators had the tips bent and 8 of the fan core stators were severely bent. The containment case remained intact. The report concluded the test successfully demonstrated the 4 pound bird ingestion test as required by 14 CFR 33.77 (a) by not catching fire, not bursting, not exceeding the engine mount loads, or losing the ability to be shut down.

14 CFR 33.76(a)(3), subsequent to Advisory Circular (AC) 33-1B, had been changed to read “…Applicants must show that the associated components when struck under the conditions prescribed in paragraphs (b), (c) or (d) of this section, as applicable, will not affect the engine to the extent that the engine cannot comply with the requirements (b)(3), (c)(6) and (d)(4) of the section.” The engine spinner is considered an “associated component.”

NTSB Probable Cause

The failure of the spinner following an unavoidable bird strike. Contributing to the incident were the inadequate engine bird strike certification requirements in place at the time the engine was certified.