148 

14 CFR Ch. I (1–1–24 Edition) 

§ 121.345 

(e) All airplanes subject to this sec-

tion are also subject to the require-
ments and exceptions stated in 
§ 121.344(g) through (k) and § 121.346. 

(f) For airplanes that were manufac-

tured before August 18, 1997, the fol-
lowing airplane types need not comply 
with this section, but must continue to 
comply with applicable paragraphs of 
§ 135.152 of this chapter, as appropriate: 
Beech Aircraft–99 Series, Beech Air-
craft 1300, Beech Aircraft 1900C, 
Construcciones Aeronauticas, S.A. 
(CASA) C–212, deHavilland DHC–6, 
Dornier 228, HS–748, Embraer EMB 110, 
Jetstream 3101, Jetstream 3201, Fair-
child Aircraft SA–226, Fairchild Metro 
SA–227. 

(g) All airplanes subject to the re-

quirements of this section that are 
manufactured on or after April 7, 2010, 
must have a digital flight data recorder 
installed that also— 

(1) Meets the requirements in 

§ 23.1459(a)(3), (a)(6), and (a)(7) or 
§ 25.1459(a)(3), (a)(7), and (a)(8) of this 
chapter, as applicable; and 

(2) Retains the 25 hours of recorded 

information required in § 121.344(g) 
using a recorder that meets the stand-
ards of TSO–C124a, or later revision. 

[Doc. No. 28109, 62 FR 38380, July 17, 1997; 62 
FR 48135, Sept. 12, 1997; 62 FR 65202, Dec. 11, 
1997, as amended by Amdt. 121–300, 68 FR 
42936, July 18, 2003; Amdt. 121–338, 73 FR 
12566, Mar. 7, 2008; Amdt. 121–338, 74 FR 32801, 
July 9, 2009; Amdt. 121–347, 75 FR 7356, Feb. 
19, 2010] 

§ 121.345 Radio equipment. 

(a) No person may operate an air-

plane unless it is equipped with radio 
equipment required for the kind of op-
eration being conducted. 

(b) Where two independent (separate 

and complete) radio systems are re-
quired by §§ 121.347 and 121.349, each 
system must have an independent an-
tenna installation except that, where 
rigidly supported nonwire antennas or 
other antenna installations of equiva-
lent reliability are used, only one an-
tenna is required. 

(c) ATC transponder equipment in-

stalled within the time periods indi-
cated below must meet the perform-
ance and environmental requirements 
of the following TSO’s: 

(1) 

Through January 1, 1992: 

(i) Any 

class of TSO-C74b or any class of TSO- 
C74c as appropriate, provided that the 
equipment was manufactured before 
January 1, 1990; or 

(ii) The appropriate class of TSO-C112 

(Mode S). 

(2) 

After January 1, 1992: 

The appro-

priate class of TSO-C112 (Mode S). For 
purposes of paragraph (c) (2) of this sec-
tion, ‘‘installation’’ does not include— 

(i) Temporary installation of TSO- 

C74b or TSO-C74c substitute equip-
ment, as appropriate, during mainte-
nance of the permanent equipment; 

(ii) Reinstallation of equipment after 

temporary removal for maintenance; or 

(iii) For fleet operations, installation 

of equipment in a fleet aircraft after 
removal of the equipment for mainte-
nance from another aircraft in the 
same operator’s fleet. 

[Doc. No. 6258, 29 FR 19205, Dec. 31, 1964, as 
amended by Amdt. 121–101, 37 FR 28499, Dec. 
27, 1972; Amdt. 121–190, 52 FR 3391, Feb. 3, 
1987] 

§ 121.346 Flight data recorders: fil-

tered data. 

(a) A flight data signal is filtered 

when an original sensor signal has been 
changed in any way, other than 
changes necessary to: 

(1) Accomplish analog to digital con-

version of the signal; 

(2) Format a digital signal to be 

DFDR compatible; or 

(3) Eliminate a high frequency com-

ponent of a signal that is outside the 
operational bandwidth of the sensor. 

(b) An original sensor signal for any 

flight recorder parameter required to 
be recorded under § 121.344 may be fil-
tered only if the recorded signal value 
continues to meet the requirements of 
Appendix B or M of this part, as appli-
cable. 

(c) For a parameter described in 

§ 121.344(a) (12) through (17), (42), or (88), 
or the corresponding parameter in Ap-
pendix B of this part, if the recorded 
signal value is filtered and does not 
meet the requirements of Appendix B 
or M of this part, as applicable, the cer-
tificate holder must: 

(1) Remove the filtering and ensure 

that the recorded signal value meets 
the requirements of Appendix B or M of 
this part, as applicable; or