CHI04LA033

The air carrier flight was substantially damaged when it impacted geese while being vectored for approach. Night visual meteorological conditions prevailed. The pilots heard a "thump." They reportedly watched the engine indications and saw nothing unusual. They visually inspected their respective wings and saw no damage. The airplane landed without incident at its destination. Inspection of the airplane revealed damage to the following areas: the vertical stabilizer front lower spare, the vertical stabilizer to the rear lower spare, the dorsal fin right hand skin panels and support structure, flange damage to rudder lower support rib for leading edge panel, and the left hand wing front spare.

On November 12, 2003, about 1915 central standard time, a Saab-Scania Saab 340B, N442XJ, operated by Mesaba Airlines Inc., as flight 2984, received substantial damage during a bird strike on approach to Minneapolis-St. Paul International Airport (MSP), Minneapolis, Minnesota. Night visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 121 scheduled domestic passenger flight was operating on an instrument rules flight plan. The two pilots, one attendant, and 22 passengers were uninjured. The flight departed from Eau Claire, Wisconsin, at 1840, and was en route to MSP where it landed without incident.

The airplane was about 47 nautical miles east of MSP at 4,000 feet mean sea level and 245 knots indicated airspeed when it encountered an unknown number of birds that impacted the airplane. The pilots heard a loud thump on the left side of the airplane and assumed they hit a goose. They immediately watched engine indications and noticed nothing unusual, and they visually inspected their respective wings and saw no damage. The pilots then contacted maintenance control and informed them of an apparent bird strike. The airplane made a visual approach to runway 12L at MSP and landed without any further problems. During a postflight inspection at the gate, the pilots were surprised at the damage to the inboard left wing and the two holes in the right side of the fuselage/tail.

According to the airplane manufacturer's Statement to Operator, Structural Repair, identified the following areas which exhibited bird strike damage: the vertical stabilizer front lower spar, the vertical stabilizer rear lower spar, the dorsal fin right hand (RH) skin panels and support structure, flange damage to the rudder lower support rib for the leading edge panel, and the left hand (LH) wing front spar stations (STAs) 80-101. This report described these areas of damage as follows:

The lower forward web was extensively damaged. The lower part of the lower stiffening bead between water line (WL) 147.5 and WL 151 was damaged. The remaining

portion of the web in this area was buckled diagonally across the center of the WL 156.3 lightning hole. The web was a bonded assembly of two webs back to back plus two additional reinforcements around the large lightning/access hole. The RH spar cap angles on the forward and the aft faces of the web were damaged (part numbers 7255317-002 and 7255317-004. The angles at WL 153 (part numbers 7255317-006, 7255317-008), the lower angle (7255315-005), the WL 153 angle (7255315-001) were also damaged.

A portion of the rear spar web between WL 147 and WL 153 was extensively damaged. The bird penetrated the web through the stiffening beads between WL 147 and WL153, and was contained in the trailing edge cove. The web is a bonded assembly of the two webs back to back plus two additional reinforcements around the large lightning/access hole. The LH spar cap angles on the rear face of the spar web were slightly bent. The two horizontal angles immediately above and below the damage (part numbers 7255325-001 and 7255325-031) were damaged.

The dorsal fin RH forward/aft skin panels (part number 7255302-633) and internal structure were extensively damaged about STA 694 and STA 745. Rib STAs 686.89, 702, 733, and 749 (part numbers 7255302-011, -013, -017, and -031) were extensively damaged.

The upper support member of the left wing for the leading edge panel (part number 7257110-205) was deformed downwards. The vertical stiffener on the front spar web at STA 101.25 (part number 7257123-095) was cracked. The clip that attaches this stiffener to the upper spar cap (part number 7257123-103) was also cracked. The channel and support for the fuel system attached to the front spar at STA 92 were also damaged. The forward flange of the spar cap was also deformed downward at the leading edge, and extended over about 11 inches and was centered around STA 95.0.

The carcass of the bird that passed through the front and rear spars of the vertical stabilizer was contained in the vertical stabilizer lower trailing edge cove, the remaining parts of the carcass were found on the rudder leading edge.

The Canada goose has more than 40 varieties. It weighs 2.4-17.6 pounds and has a wingspan of 3-6 feet. The snow goose has two main types, the greater snow goose and the lesser snow goose. The greater snow goose weighs approximately 7.7 pounds, and has a wingspan of about 5 feet. The lesser snow goose weighs approximately 6 pounds, and has a wingspan of about 3 feet.