[Code of Federal Regulations]
[Title 14, Volume 1]
[Revised as of January 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 14CFR33.43]

[Page 740-741]
 
                     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

[[Page 741]]

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 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]