A Boeing team led by Commercial Airplanes President Ray Conner is set to present details of its proposed near-term solution to the 787 battery issues to the FAA later this week, possibly as early as Feb. 21.

According to airline sources, Conner will present details of the manufacturers’ revised battery system directly to FAA Administrator Michael Huerta in Washington D.C. If the plans are accepted then Boeing is understood to have provisional plans in place to begin flight testing the modified system immediately, and for fleet-wide retrofit action which would enable the first 787 to return to service as early as mid-March.

However, given the high-profile nature of the battery probe, and the subsequent review of the FAA’s oversight in connection with the original certification of the 787, it is far from clear if the agency will even consider Boeing’s request until the National Transportation Safety Board has completed its investigation. The NTSB, and its Japanese counterpart, the JTSB, are still evaluating the root cause of multiple battery failures in early January which prompted a worldwide grounding of the 787 on Jan. 16.

Boeing, which revealed additional details of the aircraft’s battery and related electrical system features on Feb. 20, declines to comment on the upcoming appeal to the FAA or on reported details of the proposed interim battery modification. Without identifying specifics, Boeing says that details published last weekend in a local newspaper contain “significant errors and speculation.” The manufacturer adds it is “working tirelessly in cooperation with our customers and the appropriate regulatory and investigative authorities. Everyone is working to get to the answer as quickly as possible and good progress is being made.”

Boeing’s bid for approval, which is based on developing a sturdy containment system and additional sensors, comes as investigators from the JTSB reveal that two cells in the second battery of the All Nippon Airways 787 that made an emergency landing at Takamatsu Airport on Jan. 16 were “swollen.” Although the emergency was prompted by problems with the main battery, which was badly damaged by burning electrolyte, the signs of apparent degradation were found in the auxiliary power unit battery located in the aft electrical/electronic equipment bay.

The JTSB says the APU battery was initially thought to be undamaged, but adds that subsequent tomographic scans revealed evidence of slight swelling. Officials, however, say that the probe remains focused on the causes of the original failure in the main battery.

Airlines meanwhile continue to make contingency plans to cover for the continued grounding of the 787. United Airlines expects the aircraft to remain out of service through March 30, while Air India expresses hope that the 787 will be back in operation by early April.