WASHINGTON, Aug 19 (Reuters) - The U.S. Federal Aviation

Administration said on Monday it would require inspections of

Boeing 787 Dreamliners following an incident in March

when a LATAM Airlines plane went into a sudden mid-air

dive that injured more than 50 passengers.

The FAA said the apparent reason for the dive was the

uncommanded movement of the captain's seat, which caused the

auto-pilot to disconnect. The agency said it had received a

total of five reports of similar problems with the captain and

first officer seats on 787s, the most recent in June, and two

remain under investigation.

The FAA's airworthiness directive impacts 158

U.S.-registered airplanes and 737 airplanes worldwide and

requires airlines to inspect the captain's and first officer's

seats on 787-8, 787-9, and 787-10 airplanes for missing or

cracked rocker switch caps or for cracked switch cover

assemblies within 30 days.

Airlines must perform any necessary corrective actions if

issues are found.

The FAA said uncommanded horizontal movement of an occupied

seat could result in a rapid descent of the airplane and serious

injury to passengers and crew.

Boeing ( BA ) and LATAM Airlines did not immediately respond to

requests for comment.

Separately, Boeing ( BA ) said Monday it had halted test flights on

its 777-9 that is awaiting certification after a component

between the engine and airplane structure was identified as

failing to perform during a maintenance check.

The FAA said Boeing ( BA ) had informed it the company discovered a

damaged component following a 777-9 flight test last week.

Boeing ( BA ) in July began certification flight testing of its

long-delayed 777-9 with FAA regulators onboard after receiving

Type Inspection Authorization.

Boeing ( BA ) added "no near-term flight tests were planned on the

other flight test airplanes" and said the part is custom to the

777-9.