WASHINGTON, July 17 (Reuters) - The National

Transportation Safety Board said on Wednesday it had scheduled

20 hours of hearings over two days on the January Alaska

Airlines Boeing 737 MAX 9 in-flight door plug emergency

and would review oversight by U.S. safety regulators.

The NTSB said on its website the Aug. 6-7 hearings are set

to last 10 hours each day and would focus on Boeing 737 MAX

manufacturing and inspections, FAA oversight of Boeing ( BA )

and Spirit AeroSystems ( SPR ) and events surrounding the

removal of the door plug in 2023. The hearing would also review

safety management and quality management systems.

Boeing ( BA ) has faced mounting questions after a door panel

detached during a Jan. 5 flight on a new Alaska Airlines 737 MAX

9, forcing pilots to make an emergency landing while passengers

were exposed to a gaping hole 16,000 feet above the ground. The

FAA had grounded all MAX 9

airplanes for several weeks and required safety checks

before they could resume flights. The agency also has barred

Boeing ( BA ) from expanding MAX production as the agency reviews the

planemaker's practices.

The NTSB said previously that four key bolts were missing

from the door plug that blew off the Alaska Airlines flight at

16,000 feet. The Justice Department has opened a criminal

investigation into the incident.

NTSB Chair Jennifer Homendy told

Reuters in April she

expected witnesses from Alaska, Boeing ( BA ) and Spirit would

provide testimony.

The FAA and Boeing ( BA ) referred questions about the hearing to

the NTSB. Last month, the NTSB said Boeing ( BA ) could lose its status

as a party to the probe after it violated rules by providing

non-public information to media and speculating about possible

causes.

The NTSB said Boeing ( BA ) would no longer see information

produced during its probe and unlike other parties, Boeing ( BA ) would

not be allowed to ask questions of other participants at the

August hearing.

Elizabeth Lund, Boeing's ( BA ) senior vice president of

quality, who had made remarks last month that violated the rules

is expected to appear at the hearing, the NTSB said last month.

The NTSB said last month it would subpoena Boeing ( BA )

witnesses to appear at the hearing. The NTSB said Wednesday the

full investigation will take approximately one year to 18 months

from the accident to complete.