(Adds background, shares)
LONDON, Nov 16 (Reuters) - GKN CEO-designate Kevin Cummings is leaving, the British engineering company announced on Thursday, after the aerospace division he used to run took a surprise writedown, sending the shares down 9 percent.
Cummings, head of GKN Aerospace since 2014, was named in September as group chief executive to replace retiring Nigel Stein from January.
In October, the group issued a profit warning sparked by problems in the aerospace division.
It said then that its Aerospace North America division would incur a 15 million pound non-cash charge relating to revised assumptions on programme inventory and receivables balances at a plant in Alabama.
On Thursday it said a further write-off of 80 million to 130 million pounds ($105-$171 million) was likely following a review of working capital at its aerospace plants in North America.
"With the exception of the working capital write-off...all other guidance for the full year remains unchanged," it said.
Anne Stevens, currently a non-executive director, will assume the role of interim chief executive with effect from Jan. 1 2018, replacing Stein who steps down at the end of the year.
The company has launched an internal and external search for a new CEO.
($1 = 0.7605 pounds) (Reporting by Kate Holton; editing by James Davey and Jason Neely)