AIRWORTHINESS DIRECTIVE

CAA-AD-077/2002

Date of issue: July 18, 2002

AIRCRAFT - PITOT HEATER SYSTEM - INSPECTION

Applicability: Model 737-600, -700, -800, and -900 series airplanes; as listed in Boeing Alert Service Bulletin 737-24A1150, dated April 11, 2002; certificated in any category.

Effective date: July 31, 2002

Compliance: Required as indicated in FAA AD 2002-14-20.

Remarks: The compliance of this AD must be recorded in Aircraft Logbook, where applicable the requirements of this AD must be integrated into Aircraft Technical Documentation. Address inquiries concerning this AD to: Civil Aviation Authority, Airworthiness Division, Ruzyne Airport, 160 08 Prague 6, Czech Republic, tel.: 420 2 33320922, fax: 420 2 20562270.

Ing. Pavel MATOUŠEK

Director of Airworthiness Division

CAA CZ

2002-14-20 Boeing: Amendment 39-12820. Docket 2002-NM-1AD.

Applicability: Model 737-600, -700, -800, and -900 series airplanes; as listed in Boeing Alert Service Bulletin 737-24A1150, dated April 11, 2002; certificated in any category.
Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (b) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.
To prevent ice from blocking the pitot tube that provides airspeed data to the flightcrew, which could lead to the flightcrew receiving incorrect airspeed data, and result in loss of control of the airplane if the flightcrew fails to recognize that the data are incorrect, accomplish the following:

Measurement of Voltage and Corrective Actions
(a) Within 60 days after the effective date of this AD, measure the electrical voltage at the circuit breaker for the captain's pitot heater to determine if the pitot heater is connected to the correct power supply bus, per Boeing Alert Service Bulletin 737-24A1150, dated April 11, 2002.

(1) If the measurement is 100 to 122 volts alternating current (AC): No further action is required by this AD.

(2) If the measurement is not 100 to 122 volts AC: Before further flight, perform all actions associated with connecting the subject circuit breaker wire to the 115-volt AC standby power supply bus (including performing a test to ensure that the pitot heater system operates correctly, repeating the measurement of the electrical voltage at the circuit breaker for the captain's pitot heater, and troubleshooting and correcting the wire connections until the test and measurement are successful), per the service bulletin.

Alternative Methods of Compliance
(b) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

Special Flight Permits
(c) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Incorporation by Reference
(d) The actions shall be done in accordance with Boeing Alert Service Bulletin 737-24A1150, dated April 11, 2002. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Effective Date
(e) This amendment becomes effective on July 31, 2002.