Maintenance personnel at the facility during flight inspection must correct any observed discrepancy immediately, when possible. It is not necessary for maintenance personnel to adjust parameters found in tolerance. Avoid over-optimizing parameters or establishing revised references based on parameters found acceptable by flight inspection but not necessarily at their optimum values. This will prevent unwarranted "following" of facility parameters (8200.1D - US Standard Flight Inspection Manual (USSFIM), 2015).
When making corrective adjustments to radiated parameters, use every resource available to predict and produce the precise change requested or needed. Avoid “tweaking” the amount of adjustment (FAA, JO 6750.49A Maintenance of Instrument Landing Systems (ILS) Facilities, 2015). Use the following formulas:
There are several locally developed spreadsheets to assist in these calculations.
Using the FI checklists, anticipate and be ready for the next adjustment. Many times, FI has a very short window to accomplish their runs. No adjustment should take more than 60 seconds. Always notify FI personnel as soon as your have completed the adjustment and get their acknowledgement. Measure and record all readings on the FI worksheet during the runs. Ensure all required data has been obtained before the flight inspection crew departs (FAA, JO 6750.49A Maintenance of Instrument Landing Systems (ILS) Facilities, 2015).
Be sure to review the adjustments that may be required by flight inspection in the maintenance order.
Discrepancies corrected during flight inspection will be included in the flight inspection report. When it is impossible to correct a discrepancy while the flight inspection is in progress, maintenance personnel must inform flight inspection personnel and take action to correct the discrepancy as soon as possible. Immediately following correction, maintenance personnel must request another flight inspection if appropriate. Flight inspection personnel must document the discrepancies noted during the flight inspection in the associated flight inspection report (8200.1D - US Standard Flight Inspection Manual (USSFIM), 2015).
Occasionally it is necessary to make equipment adjustments that may appear to be abnormal on the basis of previous operational adjustments, or that may exceed tolerances. The need for such adjustments may be due to maladjustment elsewhere in the ground equipment, a change in terrain or multi-path environments, defective airborne equipment, radio frequency interference, or other factors (8200.1D - US Standard Flight Inspection Manual (USSFIM), 2015).
ATSSs must observe equipment performance during the flight inspection and be aware when parameters exceed tolerances or abnormal adjustments are required to satisfy flight inspection.
If measurements made with approved test equipment do not agree with the measurements reported by flight inspection personnel, you should advise flight inspection personnel and request them to repeat their measurements. If you cannot attain agreeable measurements, unless stated otherwise in the handbook, the flight inspection measurements must govern, and maintenance personnel must report the discrepancy to the Manager (8200.1D - US Standard Flight Inspection Manual (USSFIM), 2015).
When it is necessary to exceed equipment tolerances to meet flight inspection requirements, maintenance personnel must notify their manager immediately. The manager must determine whether the variance is sufficiently severe to require immediate investigation or whether you can defer investigating (FAA, JO 6750.49A Maintenance of Instrument Landing Systems (ILS) Facilities, 2015).
If you cannot make this determination prior to departure of the flight inspection aircraft, the system, subsystem, or equipment may remain in service, provided the following:
(a) The performance is stable to the extent that operation is reliable.
(b) Flight inspection personnel concur in the continued operation.
(c) The maximum rating or manufacturers specification; e.g., power output, temperature, etc. of equipment is not exceeded.
(8200.1D - US Standard Flight Inspection Manual (USSFIM), 2015)