US National Transportation Safety Board investigators are examining the manufacturing and maintenance records of the General Electric CF34-3B1 involved in last month's uncontained engine failure on a Mesa Airlines Bombardier CRJ200LR.

Investigators are looking to determine if existing fan disk inspections are appropriate and effective and whether further corrective action is warranted.

The 25 January incident resulted in a search for engine parts over mountainous terrain in Colorado. The engine history probe comes after the search uncovered around half of the fan disk, fan blades, parts of the engine cowling and thrust reverser, the engine spinner, and pieces of the fan containment case lost in the incident.

The wreckage is now at the NTSB's materials laboratory, where specialists have identified the fracture's point of origin, the NTSB reveals in a preliminary update of its investigation.

The board says that investigators are using their knowledge of the fracture surface "in their examination of the history of that [fan disk] piece", but adds that it "can't get any more specific than that".

While investigators would "like to find the mating piece to the fan disk", they are "very satisfied with the results of the search", a sentiment supported by its finding of the fracture surface "within days of the incident", the NTSB says.

The aircraft, operating as US Airways Express flight 2985 from Denver to Phoenix, was climbing through 24,000ft (7,300m) when the left engine failed, shedding components over the mountainous area.

Preliminary examination of the No 1 engine revealed that the inlet, fan rotor assembly, fan containment case and thrust reverser were missing.

Inspection of the aircraft revealed impact damage to the fuselage, in line with the plane of rotation of the engine fan rotor, as well as impact marks on the vertical and horizontal stabilisers.

The NTSB says investigators have ended their active search of engine parts, but notes that "everyone in the area has been apprised of what's out there and I wouldn't be surprised if, over time, people find" other pieces.

GE declines to comment on the investigation.

Source: Flight International