357 

Federal Aviation Administration, DOT 

§ 125.241 

(i) All airplanes required by this part 

to have a cockpit voice recorder and a 
flight data recorder, that install 
datalink communication equipment on 
or after December 6, 2010, must record 
all datalink messages as required by 
the certification rule applicable to the 
airplane. 

[Doc. No. 25530, 53 FR 26149, July 11, 1988, as 
amended by Amdt. 125–54, 73 FR 12568, Mar. 7, 
2008; Amdt. 125–54, 74 FR 32801, July 9, 2009; 
Amdt. 125–60, 75 FR 17046; Apr. 5, 2010] 

§ 125.228 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 § 125.226 may be fil-
tered only if the recorded signal value 
continues to meet the requirements of 
Appendix D or E of this part, as appli-
cable. 

(c) For a parameter described in 

§ 125.226(a) (12) through (17), (42), or (88), 
or the corresponding parameter in Ap-
pendix D of this part, if the recorded 
signal value is filtered and does not 
meet the requirements of Appendix D 
or E 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 D or E of 
this part, as applicable; or 

(2) Demonstrate by test and analysis 

that the original sensor signal value 
can be reconstructed from the recorded 
data. This demonstration requires 
that: 

(i) The FAA determine that the pro-

cedure and the test results submitted 
by the certificate holder as its compli-
ance with paragraph (c)(2) of this sec-
tion are repeatable; and 

(ii) The certificate holder maintains 

documentation of the procedure re-
quired to reconstruct the original sen-
sor signal value. This documentation is 

also subject to the requirements of 
§ 125.226(i). 

(d) 

Compliance. 

Compliance is re-

quired as follows: 

(1) No later than October 20, 2011, 

each operator must determine, for each 
airplane it operates, whether the air-
plane’s DFDR system is filtering any of 
the parameters listed in paragraph (c) 
of this section. The operator must cre-
ate a record of this determination for 
each airplane it operates, and maintain 
it as part of the correlation docu-
mentation required by § 125.226(j)(3) of 
this part. 

(2) For airplanes that are not fil-

tering any listed parameter, no further 
action is required unless the airplane’s 
DFDR system is modified in a manner 
that would cause it to meet the defini-
tion of filtering on any listed param-
eter. 

(3) For airplanes found to be filtering 

a parameter listed in paragraph (c) of 
this section, the operator must either: 

(i) No later than April 21, 2014, re-

move the filtering; or 

(ii) No later than April 22, 2013, sub-

mit the necessary procedure and test 
results required by paragraph (c)(2) of 
this section. 

(4) After April 21, 2014, no aircraft 

flight data recording system may filter 
any parameter listed in paragraph (c) 
of this section that does not meet the 
requirements of Appendix D or E of 
this part, unless the certificate holder 
possesses test and analysis procedures 
and the test results that have been ap-
proved by the FAA. All records of 
tests, analysis and procedures used to 
comply with this section must be 
maintained as part of the correlation 
documentation required by 
§ 125.226(j)(3) of this part. 

[Doc. No. FAA–2006–26135, 75 FR 7356, Feb. 19, 
2010] 

Subpart G—Maintenance 

§ 125.241 Applicability. 

This subpart prescribes rules, in addi-

tion to those prescribed in other parts 
of this chapter, for the maintenance of 
airplanes, airframes, aircraft engines, 
propellers, appliances, each item of 
survival and emergency equipment, 
and their component parts operated 
under this part.