The rusted metal aircraft part believed to be from one of the hijacked jets that were crashed into the World Trade Centre on 9/11 came from a wing, not landing gear.
Police said that the 5ft piece is a trailing edge flap support structure. It is located closer to the body of the plane and helps secure wing flaps that move in and out and aid in regulating plane speed.
Investigators initially thought it was part of the landing gear because both pieces have similar-looking hydraulics.
Boeing officials told police the part came from one of its 767 airliners, but it is not possible to determine which flight.
Both hijacked planes that struck the towers, American Airlines Flight 11 and United Airlines Flight 175, were Boeing 767s. American and United have not made any comment.
Workers discovered the part last Wednesday on the ground in a sliver of space between a luxury loft rental building and a mosque that in 2010 prompted virulent national debate about Islam and freedom of speech in part because it is near the trade centre site.
Other World Trade Centre wreckage has been discovered at the buildings and around the area in previous years. An inspector on the roof of the mosque site, which is under construction, noticed the debris and then called police.
Police documented the debris with photos. The twisted metal part - jammed in an 18in-wide, rubbish-laden passageway between the buildings - has cables and levers on it and is about 5ft high, 17in wide and 4ft long.
There is no indication that the part was planted in the space, said Paul Browne, chief spokesman for the New York Police Department.
Of the nearly 3,000 victims of the trade centre attacks, remains of about 1,000 were never recovered. Sifting of the site where the part was found for possible human remains is to begin on Tuesday morning local time.