An engine fan blade that showed signs of metal fatigue broke off, causing the emergency landing of a Southwest Airlines jet last month, investigators say.

The plane landed in Florida after shrapnel from the broken engine hit the fuselage, leaving a 5-by-16-inch hole in the outer layer of aluminum above the left wing and causing the plane to lose cabin pressure.

The National Transportation Safety Board released the details in an update Monday to its investigation of the Aug. 27 incident.

In an email, Southwest spokeswoman Lisa Tiller said the airline is “continuing to work closely with the NTSB on the investigation of this unique and extremely rare event.”

Tiller said repairs have begun on the plane but no date is known for its return to flying. She declined to comment further, saying Southwest would defer to the NTSB to provide more details about the incident.

Investigators said one blade separated from the engine fan disk during the flight. The root of the blade stayed in place, but the rest broke off and was not recovered.

The NTSB said initial laboratory findings indicated that an area of the titanium-alloy blade stub about 1 inch long and one-fifth of an inch deep showed signs “consistent with fatigue crack growth.”

Fertilizer

2 big Canadian firms to merge

Two large Canadian fertilizer giants have agreed to merge.

Agrium and the Potash Corporation of Saskatchewan signed an all-stock merger, creating the largest crop-nutrient company in the world, the companies announced Monday. After the close of the deal, Potash Corp. shareholders will own 52 percent of the company, while Agrium’s investors will own 48 percent.

The two companies produce nitrogen, potash and phosphate fertilizers, which farmers use to grow their crops.

The deal follows others that touch the farming industry, including the merger between Dow Chemical and DuPont, with plans to eventually break into three parts, one of which will focus on agricultural chemicals. China National Chemical Corp. has also agreed to acquire seed and farm chemicals producer Syngenta. And German industrial giant Bayer has been in negotiations with Monsanto, the U.S. company known for its genetically modified crop seeds.

Farm groups have raised concerns about the effect of a merger on fertilizer prices. Yet there has been little public outcry since the two companies said Aug. 30 that they were in talks.

REtail

Target plans holiday hiring

Target says it will hire more than 70,000 seasonal store workers during the busy holiday shopping season, about the same as it hired last year.

It also plans to hire an additional 7,500 people for its distribution facilities, which ship online orders and send products to stores.

The chain will hold hiring events at all 1,800 stores Oct. 14 and 15. Candidates can also apply online. Existing employees will first get to choose which extra hours they want.

Chronicle News Services