Inspections triggered by production flaws in Boeing's 787 jetliner are further slowing deliveries of the two-aisle planes, compounding Boeing's struggle to recover from the grounding of its 737 Max and the coronavirus pandemic.

Boeing said Tuesday it was inspecting separate issues that have been found where rear sections of the 787 fuselage are joined together and on part of the tail called the horizontal stabilizer.

The affected planes haven't been delivered to customers yet, and "We expect these inspections to affect the timing of 787 deliveries in the near term," spokesman Peter Pedraza said in a statement.

The Federal Aviation Administration said it is investigating the matter.

"It is too early to speculate about the nature or extent of any proposed Airworthiness Directives that might arise from the agency's investigation," said the spokesman, Lynn Lunsford, referring to potential safety orders that could be imposed on Boeing.

The Chicago-based company, which builds planes in Washington state and South Carolina, said it delivered 13 airliners last month, including four 787s, which Boeing calls the Dreamliner. It is a popular plane among airlines for international routes.

Boeing's slow pace of deliveries since early 2019 has robbed the company of much-needed cash.

During production of the horizontal stabilizer at a Boeing plant, some parts were clamped together with too much force, resulting in improper gaps between sections. Boeing doesn't believe it is an immediate safety issue but could lead to premature aging of the fuselage, and it is delaying some 787 deliveries while determining whether repairs are needed on planes that have already been delivered.

Boeing is still working with U.S. and foreign regulators to clear the Max for return to flying after two deadly crashes. Nearly 400 Max jets were in use when the fleet was grounded worldwide in March 2019 after crashes in Indonesia and Ethiopia killed 346 people. The Max was Boeing's best-selling plane.

Boeing dispatched a Max to Vancouver on Tuesday for flight tests this week with European regulators. The company has already conducted several test flights with FAA experts to demonstrate changes that Boeing made to computers and software after an automated system pushed down the noses of planes before they crashed.

The company reported Tuesday that it received orders for five Maxes in August, two to Polish charter airline Enter Air and three to a buyer that Boeing did not identify. It also reported selling three 777 cargo freighters.

However, cancellations continue to outpace new orders, and Boeing has removed other sales from its backlog because the financial health of the airline customer makes the orders uncertain.

So far this year, Boeing has lost 932 more orders than it has gained. The pandemic has undermined air travel, leading to fewer flights and leaving airlines with no need for new planes.

Boeing shares fell 4% in midday trading.