EVERETT — Factory-floor workers taking early retirements could pose a challenge to Boeing’s plans to ramp up 737 and 787 production starting next year, says Scott Hamilton, an aerospace analyst and owner of Issaquah-based Leeham Co.

That could be a greater threat to airplane delivery times than Boeing’s plan to cut about 4,000 jobs by June.

Thousands of mechanics — the men and women who assemble Boeing jetliners — will be eligible to retire by the end of the year. District Lodge 751 of the International Association of Machinists and Aerospace Workers (IAM) told Hamilton that it puts the number at between 7,000 and 9,000, and union leaders expect as many as 5,000 to retire, he writes in a column for Forbes.

Boeing will need to hire thousands of new workers, and many will likely come from other aerospace companies in Washington.

Many Boeing engineers are also approaching retirement age, according to the Society of Professional Engineering Employees in Aerospace (SPEEA), the white-collar union that represents engineers and technical workers.

About 7,500 members of SPEEA’s professional unit, which represents engineers, are older than 50, SPEEA spokesman Bill Dugovich told the Daily Herald.

That is slightly more than half of the collective bargaining unit’s 14,144 engineers.

Dan Catchpole: 425-339-3454; dcatchpole@heraldnet.com; Twitter: @dcatchpole.