NOISE MEASUREMENTS FOR A TWIN-ENGINE COMMERCIAL JET AIRCRAFT DURING 3 DEG APPROACHES AND LEVEL FLYOVERS

Noise measurements have been made with a twin-engine commercial jet aircraft making 3 deg approaches and level flyovers. The flight-test data showed that, in the standard 3 deg approach configuration with 40 deg flaps, effective perceived noise level (EPNL) had a value of 109.5 effective perceived noise decibels (EPNdB). This result was in agreement with unpublished data obtained with the same type of aircraft during noise certification tests; the 3 deg approaches made with 30 deg flaps and slightly reduced thrust reduced the EPNL value by 1 EPNdB. Extended center-line noise determined during the 3 deg approaches with 40 deg flaps showed that the maximum reference A-weighted sound pressure level (LA,max)ref varied from 100.0 A-weighted decibels 2.01 km (108 n. mi.) from the threshold to 87.4 db(A) at 6.12 km (3.30 n. mi.) from the threshold. These test values were about 3 db(A) higher than estimates used for comparison. The test data along the extended center line during approaches with 30 deg flaps were 1 db(A) lower than those for approaches with 40 deg flaps. Flight-test data correlating (LA,max)ref with thrust at altitudes of 122 m (400 ft) and 610 m (2000 ft) were in agreement with reference data used for comparison. (Author)

  • Corporate Authors:

    Langley Research Center

    National Aeronautics and Space Administration
    Hampton, VA  USA  23665
  • Authors:
    • Hastings, ECJ
    • Shanks, R E
    • Mueller, A W
  • Publication Date: 1976-7

Media Info

  • Pagination: 60 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00143282
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: NASA-TM-X-3387
  • Files: TRIS
  • Created Date: Nov 17 1977 12:00AM