* Polish flag carrier LOT plane en route from Chicago to Warsaw
* Makes emergency stop in Glasgow; no fire or smoke observed
* Boeing Dreamliner has been hit by series of technical glitches (Recasts to show plane flying to Poland)
By Anna Koper and Sarah Young
LONDON/WARSAW, Sept 26 (Reuters) - A Boeing Co Dreamliner travelling from Chicago to Poland resumed its flight on Friday after making an emergency landing at Glasgow, Scotland, to check an alert from the fire protection system in the baggage hold.
The plane, owned by Polish state airline LOT [LOT.UL, was on the ground for about 5-1/2 hours.
"After checking the aircraft, it turned out that it is functional," said LOT spokeswoman Barbara Pijanowska-Kuras, adding that firefighters at the scene did not see any fire or smoke.
Emergency services met LOT Flight 4, which was headed to Warsaw, at 9:35 a.m. local time (1035 GMT), Glasgow's airport said. Other traffic at the airport was not affected.
The plane was initially cleared as safe and the 248 passengers disembarked, an airport spokesman said. The passengers later reboarded and the plane took off around 1700 GMT and was due in Warsaw around 1900 GMT.
Boeing said it was aware of the flight diversion and was "working with our customer to assess the situation. At this time we have no further details."
The diversion of the LOT flight comes just days after the U.S. Federal Aviation Administration called for parts upgrades on the Dreamliner to ensure better fire suppression in its cargo hold and an electrical equipment bay.
Any findings of technical fault would add to earlier problems experienced by the 787 Dreamliner - Boeing's estimated $32 billion bet on new technology, which entered commercial service three years ago.
The global 787 fleet was grounded from January to April last year after two lithium-ion batteries burned out in separate incidents in Japan and the United States. The main lithium battery is housed in the electrical equipment bay that was the area of the plane targeted by the FAA action, a proposed rule published on Tuesday and agreed to by Boeing.
Boeing said the FAA action did not involve the battery. The FAA called for improving foam-like plugs in the area of the battery to prevent Halon, a fire-fighting chemical, from escaping in the event of a fire. Boeing said it agreed with the plan to install the upgraded parts on about 88 aircraft, known as the 787-8, which posed no immediate safety concern.
NO SMOKE, FIRE ON PLANE
Pijanowska-Kuras, the LOT spokeswoman, said the emergency landing was prompted by "a glitch in the fire protection system" but further details were not available. She said there was no smoke or fire on board the plane.
Earlier, she told Poland's TVN24 channel that the crew got an alert from the plane's fire protection system and diverted to the nearest airport to comply with safety rules.
The plane is one of six Boeing 787s in LOT's fleet, all equipped with engines made by Rolls-Royce Holdings PLC. Rolls-Royce declined to comment.
Boeing's state-of-the-art plane is built with carbon-fibre composite materials and a powerful electrical system to reduce weight and improve fuel efficiency.
The Dreamliner was more than three years late to enter service after issues with parts, and has since suffered a series of mishaps with brakes, fuel lines, electrical panels, hydraulics and other systems.
The company won approval for the jets to resume flying in April 2013 after it redesigned the lithium battery, charger and containment system.
In July 2013, a Dreamliner caught fire at London Heathrow Airport. British investigators traced the probable cause to faulty wiring of a lithium battery in an emergency beacon not made by Boeing.
Japan's ANA Holdings Inc, which operates the world's biggest fleet of Dreamliners, found damage to the battery wiring on two 787 locator beacons in July 2013.
Separately on Friday, German airline Air Berlin said it had cancelled orders for Boeing aircraft worth about $5 billion at list prices as it strives to curb spending and return to profitability. The cancellations included 15 787-8s and 18 Next-Generation 737-800s, Boeing said.
Boeing shares were up 0.55 percent at $127.84 in midday trading on the New York Stock Exchange.
(Additional reporting by Guy Faulconbridge, Anna Koper and Alwyn Scott; editing by Robin Pomeroy, G Crosse and Dan Grebler)