FB-111A Maintainability.

The FB-111A aircraft was conceived as a version of the F-111A with minimum modification to take advantage of the savings in manufacturing costs and support requirements over the life of the weapon system. Because of the similarity of the configuration of the F-111A and FB-111A, maintainability problems encountered and resolved on the F-111A have immeasurably benefited the FB-111A maintainability program.

Like the F-111A, the FB-111A design reflects consideration for the maintenance man. Some of the more distinctive and significant maintainability design features are; Accessibility of aircraft servicing points with minimum manipulation of covers, doors and aerospace ground equipment, and without the aid of maintenance stands. Performance of preflight inspection and turnaround servicing without ground power. Quick release engine doors and engine disconnects, which contribute to a reduction in engine change span time. Engine swing mounts, which permit access to many engine areas without removal of the engine from the aircraft. Rapid accessibility to weapons pylons to aid in loading and/or testing of pylons or stores.

Interchangeable covers, which can be replaced in approximately one-fifth to one-tenth the time required to replace a replaceable or a semi-replaceable cover. 95 percent of the FB-111A covers are interchangeable.

Accessibility of engine oil filter and dipstick through an access door which can be opened in five minutes. Oil can be checked with the dipstick, which is attached to the cap. Oil can be added directly from the can; or, if desired, a ground oil servicing cart can be used as an alternative, using the gravity-fill method.

Accessibility of avionics packages, 85 percent of which are contained in the forward equipment bay. The ballistics computer, the terrain following computer and the amplifier power supply are three examples of avionic line replaceable units (LRUs) which can be replaced in 10 minutes by a single avionic specialist.

Incorporation of a false axle design which enables removal of the wheel and tire assembly by removal of only the main wheel nut and its attached antiskid cap. The false axle is designed so that it prevent separation of the wheel halves with a fully inflated tire, thereby decreasing danger to personnel during handling. This safety factor allows wheel and tire assembly installation in the fully inflated condition. Tire deflation prior to removal is required only with severe tire damage, thus reducing the time necessary to perform the normal tire change task.

Integral dual ingress/egress provisions eliminate the necessity for portable crew ladders, thereby reducing aerospace ground equipment (AGE) requirements at advance operating bases. Crew safety is enhanced and potential damage to the aircraft adverted during transient stops by eliminating the possible use of improper ladders.

These are but a few of the design features of the FB-111A which enhance the supportability of the aircraft and reduce the maintenance man-hours per flight hour (MMH/FH).

(Reproduced with permission from General Dynamics '111Log')