Aircraft continually age in service periods while in the custody of an operating command with the following exceptions:

Due to special rework at the depot site

Due to storage while in operating command physical custody that requires special prior approval by CNO

Due to commencement of ASPA inspections or modifications

Aircraft time accumulated in nonaging situations in excess of 30 days, or a multiple thereof, requires the submission of an XRAY report. A nonaging record is maintained in the aircraft logbook. Refer to table 6-6 for information concerning XRAY status codes which require nonaging entries.

Whenever it becomes definitely known that an aircraft, because of its condition or a directive, will be returned for rework or retirement before completing the full standard service, the PED must be changed to the last month in which the aircraft will serve in the current tour. A revised end date must be reported by XRAY message. Every change in the predicted PED must be reported by XRAY message even though no other reportable actions occur.

If extensions are granted on the service or period of an aircraft, the PED is not changed. The PED is properly a past date when the aircraft is on an extension.

Some aircraft subject to SDLM will serve in period a specified number of months or be flown a specified number of hours. The period ends after either reaching the prescribed number of months or flying hours, whichever occurs first. Upon receiving the aircraft, the operating unit develops the PED by using the prescribed calendar month limitation, unless the expected use rate indicates an earlier period end date.

Since flying hours have an important bearing on the PEDs of aircraft subject to SDLM, the end dates must be reviewed periodically. If it appears. that the total flying hours prescribed for each period will be reached sooner than the end date previously predicted, a new end date must be computed based on the past average rate of flying. The new end date must be reported by XRAY message.

Item I - extension number. The first extension authorized by the controlling custodian or the number of any additional extension authorized by the Chief of Naval Operations is entered for this item. The initiation of an extension requires an XRAY report even though no other reportable action occurs. Action code X is used to describe the initiation of extensions. The number in this item pertains to extensions of the current tour or period only. Extensions granted on second or subsequent periods are renumbered starting with the number 01 in each period.

Item J - strike/damage code. If the action being reported involves the strike or damage of aircraft, the four-character strike/damage code describing the circumstance is entered in item J.

NOTE: Strike is the official action that removes an aircraft from the list of Navy aircraft. See table 6-7 for strike and damage codes.

Four categories are used to describe the main reasons for which an aircraft can be stricken. Category 5 is used for substantially damaged aircraft that are repairable. Each of these categories necessitates separate administrative procedures. These categories are discussed in the following paragraphs.

Category 1 - damage. An aircraft is stricken in category 1 if it is lost or damaged to such an extent that its restoration to serviceability would be uneconomical or militarily impractical. This category is the one most often used by operating activities.

Category 2 - depreciation. An aircraft is stricken in category 2 if it has depreciated by time and usage to such an extent that its restoration to serviceability would be uneconomical or militarily impractical. Only the Naval Air Systems Command, with approval of the Chief of Naval Operations, may declare an aircraft eligible for category 2 strike; therefore, operating activities are not involved in striking aircraft in category 2.

Category 3 - administrative. An aircraft is stricken in category 3 when it is stricken by the Chief of Naval Operations for special administrative reasons and not by reasons of damage, depreciation, or completion of full standard service life. This category includes strikes because of model obsoleteness, excess to Navy requirements, required diversion to ground training or technical use, transfer to non-Navy recipients, intentional destruction in test or