TM 1-1520-240-10            7-1-1 CHAPTER  7 712  PERFORMANCE DATA SECTION  I.  INTRODUCTION 7-1-1.  Purpose. The purpose of this chapter is to provide the best available performance data for the CH-47D helicopter.  Regular use of this information will enable you to receive maximum safe utilization  from  the  aircraft.    Although  maximum  perfor- mance is not always required, regular use of this chapter is recommended for the following reasons. a.  Knowledge of your performance margin will allow you    to    make    better    decisions    when    unexpected conditions or alternate missions are encountered. b.  Situations requiring maximum performance will be more readily recognized. c.  Familiarity with the data will allow performance to be computed more easily and quickly. d.  Experience will be gained in accurately estimating the effects of variables for which data are not presented. 7-1-2. General Data. The data presented covers the maximum range of condi- tions and performance that can reasonably be expected. In each area of performance, the effects of altitude, tem- perature, gross weight (GW), and other parameters re- lating to that phase of flight are presented.  In addition to the presented data, your judgement and experience will be necessary to accurately obtain performance under a given set of circumstances.  The conditions for the data are listed under the title of each chart.  The effects of different conditions are discussed in the text accompany- ing each phase of performance.  Where practical, data is presented  at  conservative  conditions.    However,  NO GENERAL CONSERVATISM HAS BEEN APPLIED.  All performance data presented is within the applicable lim- its of the aircraft. CAUTION Exceeding operating limits can cause per- manent  damage  to  critical  components. Over limit operation can decrease perfor- mance, cause immediate failure, or failure on a subsequent flight. 7-1-3.  Limits. Applicable  limit  lines  are  shown  on  the  charts.    The dashed lines on the cruise charts are estimated airspeed limits  with  an  operating  cruise  guide  indicator  (CGI). Airspeed limits with the CGI inoperative are in Chapter 5. If limits are exceeded, minimize the degree and time. 7-1-4.  Use of Charts. a.  Chart Explanation.  The  first page of each section describes the chart(s) and explains its use. b.  The primary use of each chart is given in an exam- ple and a guideline is provided to help you follow the route through the chart.  The use of a straight edge (ruler or  page  edge)  and  a  hard  fine  point  pencil  is  recom- mended to avoid cumulative errors.  The majority  of the charts  provide  a  standard  pattern    for use as follows: enter first variable on the top left scale, move right to the second variable, deflect down at right angles to the third variable, deflect left at right angles to the fourth variable, deflect down, etc. until the final variable is read out at the final scale.  In addition to the primary use, other uses of each chart are explained in the text accompanying each set of performance charts. NOTE An example of an auxiliary use of the charts referenced above is as follows: Although the hover   chart   is   primarily   arranged   to   find torque required to hover, by entering torque available as torque required, maximum wheel height for hover can also be found.  In general, any single variable can be found if all others are known.  Also, the tradeoffs between vari- ables can be found.  For example, at a give pressure altitude (PA), you can find the maxi- mum GW capability as free air temperature (FAT) changes. c.  Dashed  Line  Data.  Data  beyond  conditions  for which tests were conducted, or for which estimates are used, are shown as dashed lines. 7-1-5.  Data Basis. The type of data used is indicated at the bottom of each performance chart under DATA BASIS.  The applicable report and date of the data are also given.  The data provided generally is based on one of the following cate- gories. a.  Flight Test Data.  Data obtained by flight test of the aircraft by experienced flight test personnel at precise conditions using sensitive calibrated instruments.