While the U.S. Air Force and Boeing [BA] have embarked on a path to fix the four remaining Category 1 deficiencies of the KC-46 tanker, the latter now may have a waste problem, literally.

“I understand there’s an issue that I had not heard about with respect to the [KC-46] transportable galley lavatory system–essentially bathrooms–that make missions problematic,” Sen. Jeanne Shaheen (D-N.H.) told Army Gen. Stephen Lyons, the commander of U.S. Transportation Command (TRANSCOM), at a Senate Armed Services Committee (SASC) hearing on Apr. 13. “Is this a new problem, or have we known about this, and what’s the prospect to fix it?”

Shaheen also wondered whether the problem would delay the expected start of KC-46 operational missions this summer.

Lyons said that he did not know of the lavatory problem and referred questions on it to the Air Force.

Air Mobility Command (AMC) said on Apr. 14 that the legacy Air Transportable/Galley Lavatory (ATGL) design is a palletized unit that has been in service since the early 1980s and contains multiple bathrooms and galley features, including beverage production and refrigeration capabilities. Flown aboard the KC-46 and other AMC aircraft, the ATGLs have three issues that affect their operational use, per AMC.

“First, many ATGL units are unserviceable or only partially mission capable as Air Mobility Command and the Air Force Life Cycle Management Center work to address continuation of the sustainment contract,” according to an Apr. 14 email from AMC. “Second, ATGLs require a restraint modification upgrade, currently in coordination, to ensure they remain safely attached to the floor pallet. Third, the unique floor cargo loading restrictions on the KC-46 require the ATGL to be flown on its narrow axis instead of the wide axis as designed. This configuration has resulted in spillage issues during steep ascents and descents.”

“AMC is testing for a potential solution to this spillage issue currently being worked,” per AMC. “The KC-46 program office plans to modify six ATGLs over the next twelve weeks to address the growing demand by the KC-46A enterprise, as it begins limited operational use in support of U.S. Transportation Command taskings. These six modified units will be evenly divided between McConnell AFB [Kans.], Pease ANGB [N.H.] and Seymour Johnson AFB [N.C.]. Until ATGLs are provided to KC-46 units, aircrew are able to utilize a built-in lavatory while conducting operations in support of all three of the KC-46’s primary missions, including airlift, aeromedical evacuation, and aerial refueling.”

Last October, Collins Aerospace [RTX] and Texas-based Knight Aerospace said that they had introduced a modern ATGL for military cargo aircraft and the KC-46 to replace “costly-to-maintain systems with a modern solution that serves military personnel during long missions.”

The companies’ ATGL is to have a full-service galley and two lavatories on a customized pallet for the military planes.

Knight Aerospace CEO Bianca Rhodes said that the legacy “blue water” ATGLs on military aircraft “are well past their obsolescence age and finding the correct parts to fix what’s currently available is becoming increasingly difficult.”

The companies said that their ATGL lavatories come with Collins Aerospace’s advanced vacuum wastewater system and Agile toilet, both of which increase “sanitary measures onboard the aircraft” and do away with the use of “blue water” systems that rely on special service trucks to pump out waste after each flight.

“We are pretty much completed with a product to replace the existing [‘blue water’] ATGLs,” Rhodes said in a phone interview on Apr. 13.

Rhodes said that the Collins Aerospace/Knight Aerospace prototype ATGL will be ready next month and that the companies plan to deliver their first ATGL unit before the end of this year.