Al Jazeera has found that some Boeing workers have serious concerns about the safety of the 787 "Dreamliner" aircraft.

In a new documentary, Broken Dreams: The Boeing 787, current and retired Boeing employees discuss their worries about quality control with Al Jazeera's Investigative Unit.

Boeing's 787 "Dreamliner", which made its first commercial flight in late 2011, has been dogged with problems since plans for its launch were announced in 2003.

Two battery failures in January 2013 sparked safety fears and led to fleets being temporarily grounded worldwide for over three months.

Boeing says it does not compromise on product safety or quality.

Whistleblower

A worker at one of two Boeing 787 assembly lines in Charleston, in the US state of South Carolina, contacted Al Jazeera's Investigative Unit to share his worries about the "Dreamliner".

The worker, speaking on condition of anonymity, says "with all the problems reported on the 787, there's 90 percent that's getting swept away".

He describes the troubles with the plane as "an iceberg". He claims only 10 percent of problems are visible to the flying public, with the rest "hushed up".

"I've seen a lot of things that should not go on at an airplane plant," the worker says. "It's been eating me alive to know what I know, and have no avenue, no venue to say anything."

In a statement to Al Jazeera, Boeing says that "787 airplanes delivered from both South Carolina and Washington final assembly and delivery operations meet the highest safety and quality standards that are verified through robust test, verification and inspection processes".

Ten of 15 'wouldn't fly'

Using a concealed camera, the worker films inside the Boeing South Carolina plant, recording his discussions with colleagues.

The number one focus that we have at Boeing is ensuring the continued safe airworthiness of an airplane. - Larry Loftis, Boeing Vice President and General Manager of the 787 "Dreamliner" Program

He randomly asks 15 of his co-workers who assemble the 787 "Dreamliner" if they would fly on the plane. Ten say they would not.

"I wouldn't fly on one of these planes," one worker tells him, "because I see the quality of the fu**ing sh*t going down around here".

Another worker replies, "it's sketchy". Asked what he means, the worker adds, "yeah I probably would, but I kind of have a death wish too".

A third says of the 787s assembled at South Carolina, "we're not building them to fly. We're building them to sell. You know what I'm saying?"

Larry Loftis, Boeing Vice President and General Manager of the 787 "Dreamliner" Program, told Al Jazeera, "The number one focus that we have at Boeing is ensuring the continued safe airworthiness of an airplane, the integrity of the airplane and the quality of the airplane going out".

Drugs

The Boeing worker also says that he is concerned that some of his colleagues are on drugs, saying he has seen "people talking about doing drugs, looking for drugs", specifically marijuana, cocaine and prescription painkillers.

In the footage, he records one man saying: "It's all coke and painkillers" at the plant, adding, "you can get weed here, you can get some really good weed here".

Another complains that Boeing "don't drug test nobody", adding that "there's people that go out there on lunch and smoke one up".

In 2011, US federal agents raided a separate Boeing plant in Philadelphia as part of a drugs investigation. They arrested dozens of workers at the facility, which builds aircraft including the H-47 Chinook helicopter and the V-22 Osprey.

In a statement to Al Jazeera, Boeing says "drug testing of employees is done in accordance with Boeing policy and procedures across all facilities in accordance with applicable laws. Boeing thoroughly investigates any employee reports of policy deviation, and appropriate corrective action is taken if needed."

Memo

A memo obtained by Al Jazeera's Investigative Unit also shows that in 2010, Boeing altered its quality standards at a time when the 787 was already two years delayed.

The source of the memo, a veteran Boeing engineer, says it reveals that the company "changed basic engineering principles to meet schedule".

On seeing the document, another long-time Boeing engineer says "they're short-changing the engineering process to meet a schedule… I find that reprehensible".

Cynthia Cole, former president of Boeing's engineers union SPEEA, adds that she would no longer fly on a Boeing 787. "I've been kind of avoiding flying on a 787 and seeing this, I would definitely avoid flying on a 787."

Boeing says its memo is fully consistent with the company's robust quality assurance system. "While we will not discuss in detail our proprietary production processes, we note that the document itself concludes by saying that the process changes 'do not signify authorisation to ship or accept parts which do not meet engineering and quality requirements.' "

The company also says that it uses one, FAA-approved quality system for the 787 in both of its assembly plants.

Follow Will Jordan on Twitter: @Willjordan

Broken Dreams: The Boeing 787 is available from Wednesday, September 10 at aljazeera.com/Boeing787.

The documentary airs on Al Jazeera English at the following times: Wednesday, September 10 at 2000 GMT; Thursday, September 11 at 0100 GMT and 1200 GMT; Friday, September 12 at 0600 GMT; Saturday, September 13 at 2000 GMT; and Sunday, September 14 at 0100 GMT.

The film airs on Al Jazeera Arabic at the following times: Wednesday, September 10 at 2205 KSA; Thursday, September 11 at 0305 KSA; Friday, September 12 at 1405 KSA; Saturday, September 13 at 1005 KSA; and Sunday, September 14 at 1705 KSA.