FLIGHT PLANS

Proper Methodology Used to Smooth the OH-58D

Table 1. OH-58D Flight Plans and Test States

TM-1-6625-724-13P Aviation Vibration Analyzer Manual
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TM 1-6625-724-13&P 0073 00 0073 00-5 NOTE Past problems with AVA software have been related to the balance characteristics of the OH-58D at idle and track data errors if proper steps are not made to insure high quality track data. Bell has not altered the basic methods to track and balance the rotor of the OH-58D for six years and have been used on 200+ new and retrofit deliveries. Recent experience has shown them clearly superior to “home grown” methods. The new 65%NRC approach is designed to improve balancing at idle. Exact control of rpm is critical. FLIGHT PLANS The OH-58D flight plans are listed below with a brief description of their purposes. The selectable flight plans are listed in order of appearance in the menu on the CADU and not in the order in which they are to be performed. Tables 1 (OH-58D) and 2 (OH-58DM) list those Test States that are associated with each flight plan. FLI-SG This flight plan is used to acquire data in flight (FLI). FLI-SG is used with aircraft equipped with standard landing gear (SG). Data is used to produce corrections using weights and trim tabs (the pitch change links are defaulted to OFF). This program assumes that the criteria of the GRDTRK and INT-SG have been met. While track is measured and recorded for each test condition, the ride quality is the deciding factor in releasing the aircraft for service. GNDTRK This flight plan is designed to get the main rotor into a perfect mechanical track (all blades within 0.2 inches of each other). Data is used to produce corrections using pitch change links (weight is defaulted to OFF). If the low RPM track (65% Nr) goal is achieved, the pitch change links may not require additional adjustments in subsequent flight Plans. It should be the first test that is performed after any component change or major rework on the main rotor. Ensuring that the ground track is below limits may reduce the time required for initial and in-flight rotor smoothing. INT-SG This flight plan is used to acquire data for an initial (INT) setting. INT-SG is used with aircraft equipped with standard landing gear (SG). Data is used to produce corrections using weights, pitch change links and trim tabs. This is the only flight plan that uses all three adjustments. This flight plan is also designed to adjust the main rotor into a perfect mechanical track, but will also give a balance solution. This flight plan should not be abandoned until track at Idle is <0.2 inches, the track change from Idle to 35%_TQ is <0.2 inches and fore/aft vibration is <0.2 ips. TAIL This flight plan is designed to balance the tail rotor. The program is the same regardless of the type of aircraft selected (OH-58D or OH-58DM). Data is used to produce corrections using weights for a chordwise or spanwise imbalance.

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