[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: 14CFR33.27]



[Page 771-772]

 

                     TITLE 14--AERONAUTICS AND SPACE

 

CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION

 

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

 

               Subpart B_Design and Construction; General

 

Sec. 33.27  Turbine, compressor, fan, and turbosupercharger rotors.



    (a) Turbine, compressor, fan, and turbosupercharger rotors must have 

sufficient strength to withstand the test conditions specified in 

paragraph (c) of this section.

    (b) The design and functioning of engine control devices, systems, 

and instruments must give reasonable assurance that those engine 

operating limitations that affect turbine, compressor, fan, and 

turbosupercharger rotor structural integrity will not be exceeded in 

service.

    (c) The most critically stressed rotor component (except blades) of 

each turbine, compressor, and fan, including integral drum rotors and 

centrifugal compressors in an engine or turbosupercharger, as determined 

by analysis or other acceptable means, must be tested for a period of 5 

minutes--

    (1) At its maximum operating temperature, except as provided in 

paragraph (c)(2)(iv) of this section; and

    (2) At the highest speed of the following, as applicable:

    (i) 120 percent of its maximum permissible r.p.m. if tested on a rig 

and equipped with blades or blade weights.

    (ii) 115 percent of its maximum permissible r.p.m. if tested on an 

engine.

    (iii) 115 percent of its maximum permissible r.p.m. if tested on 

turbosupercharger driven by a hot gas supply from a special burner rig.

    (iv) 120 percent of the r.p.m. at which, while cold spinning, it is 

subject to operating stresses that are equivalent to those induced at 

the maximum operating temperature and maximum permissible r.p.m.



[[Page 772]]



    (v) 105 percent of the highest speed that would result from failure 

of the most critical component or system in a representative 

installation of the engine.

    (vi) The highest speed that would result from the failure of any 

component or system in a representative installation of the engine, in 

combination with any failure of a component or system that would not 

normally be detected during a routine preflight check or during normal 

flight operation.



Following the test, each rotor must be within approved dimensional 

limits for an overspeed condition and may not be cracked.



[Amdt. 33-10, 49 FR 6851, Feb. 23, 1984]