[Code of Federal Regulations]

[Title 14, Volume 1]

[Revised as of January 1, 2006]

From the U.S. Government Printing Office via GPO Access

[CITE: 14CFR33.43]



[Page 773-774]

 

                     TITLE 14--AERONAUTICS AND SPACE

 

CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION

 

PART 33_AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES--Table of Contents

 

          Subpart D_Block Tests; Reciprocating Aircraft Engines

 

Sec. 33.43  Vibration test.



    (a) Each engine must undergo a vibration survey to establish the 

torsional and bending vibration characteristics of the crankshaft and 

the propeller shaft or other output shaft, over the range of crankshaft 

speed and engine power, under steady state and transient conditions, 

from idling speed to either 110 percent of the desired maximum 

continuous speed rating or 103 percent of the maximum desired takeoff 

speed rating, whichever is higher. The survey must be conducted using, 

for airplane engines, the same configuration of the propeller type which 

is used for the endurance test, and using, for other engines, the same 

configuration of the loading device type which is used for the endurance 

test.

    (b) The torsional and bending vibration stresses of the crankshaft 

and the propeller shaft or other output shaft may not exceed the 

endurance limit stress of the material from which the shaft is made. If 

the maximum stress in the shaft cannot be shown to be below the 

endurance limit by measurement, the vibration frequency and amplitude 

must be measured. The peak amplitude must be shown to produce a stress 

below the endurance limit; if



[[Page 774]]



not, the engine must be run at the condition producing the peak 

amplitude until, for steel shafts, 10 million stress reversals have been 

sustained without fatigue failure and, for other shafts, until it is 

shown that fatigue will not occur within the endurance limit stress of 

the material.

    (c) Each accessory drive and mounting attachment must be loaded, 

with the loads imposed by each accessory used only for an aircraft 

service being the limit load specified by the applicant for the drive or 

attachment point.

    (d) The vibration survey described in paragraph (a) of this section 

must be repeated with that cylinder not firing which has the most 

adverse vibration effect, in order to establish the conditions under 

which the engine can be operated safely in that abnormal state. However, 

for this vibration survey, the engine speed range need only extend from 

idle to the maximum desired takeoff speed, and compliance with paragraph 

(b) of this section need not be shown.



[Amdt. 33-6, 39 FR 35465, Oct. 1, 1974, as amended by Amdt. 33-10, 49 FR 

6851, Feb. 23, 1984]