Iranian overhauled Tomcat F-14
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Here is an excerpt from a thesis on the American overhaul process of The Tomcat just to see how complicated it is:
Total of 249 Days
1. The F-14 Overhaul Process
The TAT for the F-14 overhaul process begins when the
aircraft arrives from the squadron to NADEP's test line.
The initial phase is the Induction/Preserve Phase. NADEP
personnel review the aircraft logbooks and Aircraft
Discrepancy Book (ADB) in order to familiarize themselves
with the maintenance history of the aircraft. Concurrently,
the aircraft's engines are operated and a complete systems
check is accomplished in order to determine a base line for
the aircraft. This base line identifies any specific,
inherent features of the aircraft as well as any
malfunctions related to that particular aircraft. At this
point, the aircraft is defueled, and the next phase begins.
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The Pre-Strip Phase starts with the removal of the
engines and primary heat exchange unit. Both aircraft
engines and the heat exchange unit are preserved and stored
in climate controlled buildings to protect them from
humidity.
After Pre-strip, the aircraft is towed from the test
flight line to the paint removal building for the Strip
Phase. During this phase the paint is chemically removed
using brushes and solvent. The allotted time for this phase
is five days. However, the actual time to complete this
phase averages approximately eight days. The reason for
this three-day schedule slip is due to excessive layers of
paint that often cannot be removed chemically. This results
in time-consuming efforts to manually sand and grind
particular areas of the aircraft.
Upon being stripped to bare metal, a light green primer
coating is applied to the aircraft. The aircraft is then
towed from the strip hangar to the main SDLM hangar, where
it is stationed for the majority of the SDLM process. All
aircraft remain in the same location and artisans move from
aircraft to aircraft completing various repairs and
modifications as required.
Once in the SDLM hangar, the Post-Strip Phase begins.
This includes opening all aircraft panels, disassembling the
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aircraft, removing the major avionics components, as well as
both the Pilot and Radar Intercept Officer ejection seats.
In the disassembly of the aircraft, the wings and both sets
of vertical and horizontal stabilators are removed and sent
to the component shop for inspection and any necessary
repairs.
Noting all discrepancies above and beyond those
identified during the ASPA inspection is the responsibility
of the Examiners and Evaluators (E&E) . It is at this point
where a determination is made as to which discrepancies are
in fact Depot-level responsibilities, and which
discrepancies are Organizational or Intermediate level
responsibilities. Discrepancies that are deemed correctable
at the two lower levels of maintenance are labeled as "Noted
But Not Corrected" (NBNC) discrepancies.
The Metal Repairs/Modifications Phase is allotted
approximately 104 days TAT. The actual time to complete
this phase averages 152 days. Although this phase is
allotted the greatest amount of time, the actual work in
direct support of SDLM is minor. The majority of the work
involves incorporation of major Airframe Changes (AFCs) .
The most common AFCs that are currently incorporated are:
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- 5K and 7K upgrades that are incorporated as the
aircraft reaches 5,000 and 7,000 flight hours
respectively;
- AFC 794/795, ALR-67 Upgrade;
- AFC 844, Modification for the Tactical Airborne
Reconnaissance Pod System (TARPS) and Digital Tarps
capability;
- AFC 859, Wing Crack Repair; and
- AFC 873, Replacement of Fuselage Station 353 Frame.
After all modifications and repairs are completed, the
Assembly 1 Phase begins. This phase includes assembling the
aircraft to the point where the fuel cells are installed and
capable of holding fuel. A Fuel Cell (Wet Check) Phase is
then conducted and includes fueling the aircraft to
capacity, and performing fuel transfer checks and fuel leak
checks. Additionally, during this phase, the engine inlet
ducts are painted as a matter of a time saving convenience
as the engines are not yet installed.
The Assembly 2 Phase requires the aircraft to be fully
assembled with the exception of aircraft panels. This
includes reinstalling both wings as well as both sets of
vertical and horizontal stabilators, the engines and the
heat exchange unit. The Final Close Operations Phase
includes applying electrical power to perform
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electronic/avionics system checks, operating aircraft
landing gear as well as installing the Pilot and Radar
Intercept Officer ejection seats.
The Ground Check/Flight Test Phase includes
installation of all access doors along with the remaining
aircraft panels onto the aircraft. A Low-Power-Turn-Up
(LPTU) and High-Power-Turn-Up (HPTU) is performed on the
aircraft. After each turn-up is complete, any discovered
discrepancies are fixed and the aircraft is scheduled for a
Post-Maintenance Check Flight. Aircrews assigned to NADEP
perform the check flight and record the results.
Upon successful completion of the test flight, the
aircraft is towed to the paint hangar for the Clean and
Final Paint Phase. During this phase, the aircraft is
thoroughly cleaned and receives a final nose-to-tail paint-
job. No special or customized paint schemes other than
normal exterior markings and insignias as directed by the
appropriate maintenance manuals are authorized.
After the paint process is completed, the aircraft
logbooks and Aircraft Discrepancy Book are reviewed and
annotated for transfer back to the squadron. A Ready- for
Issue (RFI) aircraft is then flown back to the fleet
squadron where it is put back into operational service.
Full text of "A comparative analysis of the efficiency and effectiveness of the F-14 Tomcat overhaul process"
