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Federal Register / Vol. 86, No. 247 / Wednesday, December 29, 2021 / Proposed Rules applicability of this proposed AD. The FAA is proposing to require installation of the newly-designed OBV as a terminating action to the repetitive inspections required for CF348C model turbofan engines. The FAA is also proposing to require replacement of certain OBVs installed on CF348E
model turbofan engines.

NPRM. Submissions containing CBI
should be sent to Scott Stevenson, Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.
Background The FAA issued AD 20192205, Amendment 3919784 84 FR 63569, November 18, 2019, AD 20192205, for all GE CF348C1, CF348C5, CF34
8C5A1, CF348C5B1, CF348C5A2, and CF348C5A3 model turbofan engines.
AD 20192205 was prompted by multiple reports of fuel leaks, some leading to engine fires, that have occurred as a result of malfunctions related to the OBV. AD 20192205
requires initial and repetitive inspections of the OBV fuel tubes, OBV
bleed air manifold link rod assemblies, and the OBV fuel fittings. AD 201922
05 also requires replacement of OBVs or related OBV hardware that fail inspection. The agency issued AD 2019
2205 to prevent failure of the OBV.
Actions Since AD 20192205 Was Issued Since the FAA issued AD 201922
05, the manufacturer redesigned the OBV to eliminate the need for the repetitive inspections of the OBV fuel tubes, OBV bleed air manifold link rod assemblies, and the OBV fuel fittings.
The manufacturer has issued service information specifying procedures to replace certain OBVs installed on CF34
8C1, CF348C5, CF348C5A1, CF34
8C5B1, CF348C5A2, CF348C5A3
CF348C, and GE CF348E2, CF34
8E2A1, CF348E5, CF348E5A1, CF34
8E5A2, CF348E6, and CF348E6A1
CF348E model turbofan engines.
Additionally, the FAA determined that the CF348E model turbofan engines are susceptible to the same unsafe condition as the CF348C model turbofan engines, and therefore, added the CF348E
model turbofan engines to the
FAAs Determination The FAA is issuing this NPRM after determining that the unsafe condition described previously is likely to exist or develop on other products of the same type design.
Related Service Information Under 1
CFR Part 51
The FAA reviewed GE CF348C
Service Bulletin SB 750020 R04, dated May 10, 2019 GE SB 750020.
The SB specifies procedures for inspecting the bleed air manifold link rod assemblies; the supply, return, and drain fuel fittings; and the fuel tubes on the OBV. The SB also specifies procedures for performing corrective actions and replacing any OBVs or related OBV hardware that fail the inspection criteria. The Director of the Federal Register approved the incorporation by reference of GE SB 75
0020 as of December 23, 2019 84 FR
63569, November 18, 2019.
The FAA reviewed GE CF348C SB
750025 R01, dated August 1, 2019.
This SB describes procedures for replacing and upgrading the suspect population of OBVs VIN 5000728104
part number P/N 4123T71P02, VIN
5000728106 P/N 4123T71P03, and VIN 5080046101 P/N 4123T71P04.
The FAA reviewed GE CF348E SB
750019 R01, dated August 1, 2019.
This SB describes procedures for replacing and upgrading the suspect population of OBVs VIN 5000728104
P/N 4123T71P02, VIN 5000728106
P/N 4123T71P03, and VIN 5080046
101 P/N 4123T71P04.
This service information is reasonably available because the interested parties
have access to it through their normal course of business or by the means identified in ADDRESSES.
Other Related Service Information The FAA reviewed GE CF348C SB
750026 R00, dated February 21, 2020.
This SB introduces OBV VIN 5080046
103 P/N 4123T71P06.
The FAA also reviewed GE CF348E
SB 750021 R00, dated February 21, 2020. This SB introduces OBV VIN
5080046103 P/N 4123T71P06.
Proposed AD Requirements in This NPRM
This proposed AD would retain certain requirements of AD 20192205.
This proposed AD would require initial and repetitive inspections of the OBV
fuel tubes, OBV bleed air manifold link rod assemblies, and the OBV fuel fittings and replacement of OBVs or related OBV hardware that fail inspection. As a terminating action to the repetitive inspections of the OBV
fuel tubes, OBV bleed air manifold link rod assemblies, and the OBV fuel fittings, this proposed AD would require replacement of certain OBVs installed on GE CF348C model turbofan engines.
This proposed AD would also require replacement of certain OBVs installed on CF348E model turbofan engines.
Differences Between This Proposed AD
and the Service Information GE SB 750020 specifies that the results of the inspections must be documented in an inspection chart form and sent to GE Product Support Engineering. This proposed AD would not mandate sending information to GE
Product Support Engineering.
Costs of Compliance The FAA estimates that this AD, if adopted as proposed, would affect 1,172
engines installed on airplanes of U.S.
registry.
The FAA estimates the following costs to comply with this proposed AD:

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ESTIMATED COSTS
Action
Labor cost
Replace OBV
Inspect OBV fuel tubes, assemblies, and fittings.

2 work-hours $85 per hour = $170
1 work-hour 85 per hour = 85

The FAA estimates the following costs to do any necessary replacements that would be required based on the
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results of the proposed inspection. The agency has no way of determining the
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Cost per product
Parts cost
Sfmt 4702

$17,230
0

$17,400
85

Cost on U.S.
operators $20,392,800
99,620

number of aircraft that might need this replacement.

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