2022年1月机队出现运行中克鲁格襟翼损伤的问题，一线提出了标准判定的问题，此前和波音做过沟通，SR3-5126464525。对于损伤原因损坏，波音认为与活动部件相关的正常磨损项目、飞行过程中的正常振动或运动以及基于飞行控制校装的异常磨损。
对于标准，波音提出的标准如下。
In general, if any portion or length of a typical non-metallic bulb or blade seal is damaged (worn, split, frayed) and installed (not missing) and the seal is still performing its intended function, there is no requirement to apply the CDL (if available) or replace the seal. If the seal length is altered (a portion removed), the configuration has been changed and an appropriate CDL should be applied (if available) or the seal should be replaced. We would review repairs on a case-by-case basis. As there are no damage tolerances published in the AMM, HNA could consider defining or categorizing seal damage ‘in-house’ to clarify if such a seal is meeting its intended function. Damage could be categorized in the following fashion:
Category 1: Damage that affects only the surface of the seal without penetrating the outer cloth. This damage can be left as is permanently. This damage does not affect the functionality of the seal. The CDL would not apply.
Category 2: Damage that is up to .25″ wide by 1 inch in length that does not fully penetrate the seal wall can be left as is until the next C-Check. This damage does not affect the functionality of the seal. The CDL would not apply.
Category 3: Damage that is up to .25″ wide by 2 inches in length that does not fully penetrate the seal wall can be left as is until the next A-Check. Regular inspections should be performed at intervals of 10 to 20 Flight Cycles to ensure that the seal does not become fully penetrated or exceed the given criteria.
