I know that regular maintenance of aircraft is important, including but not limited to aircraft engaged in aerial wildland firefighting. Maintenance in the United States and in other countries does not happen on a haphazard schedule but is on a schedule partly dependent on how many take-offs and landings (one take-off and landing is called a cycle) the aircraft has flown. However, I believe that there is more to the frequency of maintenance than just cycles flown. As I am not airframe and powertrain mechanic nor do I work for a company flying aircraft on wildland fires so I am not in a position to speak knowledgeable about the specifics of aircraft maintenance. But I can say that I know enough to know how important it is that the maintenance be performed on schedule, rigorously and thoroughly.
In June 2021, Coulson's Australia Division shared a short video on their Facebook page describing winter maintenance of their aircraft based in Australia. While a different country, they do provide an overview of the maintenance performed during the Australian winter. I shared this video (under two minutes) on my blog in June 2021
While wildfire season is almost year round in some parts of the western United States, most but not all aircraft flying fires are on some kind of contract with the federal or a state government agency. This means that they are off contract for a part of the years and it is during this time when maintenance requiring a longer time to perform is done. Earlier this year, March 4, 2022 to be exact, Aerial Fire had a nice article on Neptune Aviation Servces' Winter Maintenance Assures Year-Round Readiness, this article may be found on this page from Aerial Fire. It is a very good article (with pictures), I appreciated the article and am a little more knowledgeable about maintaining an airtanker. Clifford Lynn, Neptune's Director of Maintenance. I encourage you to take a few moments to read this article. According to Mr. Lynn:
Neptune’s maintenance team designed the FAA-approved airframe inspection program (AIP), which builds upon BAE Systems’ OEM maintenance protocol for the aircraft as a commercial jet.
As he described it, every year, each aircraft gets an A Check, a C phase check, and a D phase check. Every two years the C check is completed and every four years the D check is completed. These C and D phase checks include a corrosion control and structural inspection program. The airframe, retardant tanks, and the engines are what the winter maintenance primarily targets.
“We schedule our winter maintenance, so anything due in the next 12 months, 400 hours, and/or 600 cycles is complied with during the heavy (C and D) check,” said Lynn. “To date, the nine air tankers are averaging 300 cycles per year. Some line replaceable units (LRU) are not changed during the checks if they have significant time on them remaining.”
Lynn added that for most life-limited components such as the landing gear, oxygen, and fire bottles, Neptune follows the OEM maintenance protocol.
Because of the stressful environment in which the aircraft fly, some components have to be inspected at more frequent intervals, he noted. “Also, we have some additional tank-related inspections.” (obtained on November 7, 2022 from https://aerialfiremag.com/2022/03/04/neptune-aviation-services-winter-maintenance-assures-year-round-readiness/
I am sure that other aircraft companies perform appropriate maintenance on all their aircraft including but not limited to aircraft flying fires in some capacity. Thanks to all who flew fires this year helping the crews on the ground put out the wildfires.