We are proposing this AD because we evaluated all information and determined the unsafe condition described previously is likely to exist or develop on other products of the same type design. This proposed AD would require you to remove the current preformed packing, elbow fitting, and jam nut from the left and right hydraulic pump pressure output port and replace with new parts. This proposed AD would also require you to install a hydraulic pump case drain check valve. Costs of Compliance

We estimate that this proposed AD would affect 182 airplanes in the U.S. registry.

We estimate the following costs to do the proposed modifications: Total cost per Total cost on Labor cost Parts cost airplane U.S. operators Hydraulic pressure output fitting assembly: 8 workhours x $80 $100 $740 $134,680 per hour = $640................................................ Hydraulic Pump Case Drain Check Valve: 16 workhours x $80 per 4,353 5,633 1,025,206 hour = $1,280..................................................

HBC will provide warranty credit as specified in Hawker Beechcraft Mandatory Service Bulletin SB 293869, dated January 2008; and Hawker Beechcraft Mandatory Service Bulletin SB 293851, dated January 2008. Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, ``General requirements.'' Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify that the proposed regulation:

1. Is not a ``significant regulatory action'' under Executive Order 12866;

2. Is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and

3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket. Examining the AD Docket

You may examine the AD docket that contains the proposed AD, the regulatory evaluation, any comments received, and other information on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone (800) 6475527) is located at the street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt. List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety. The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows: PART 39AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.
[[Page 23990]]

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by adding the following new AD: Hawker Beechcraft Corporation: Docket No. FAA20080492; Directorate Identifier 2008CE023AD.
Comments Due Date
(a) We must receive comments on this airworthiness directive (AD) action by June 30, 2008.
Affected ADs
(b) None.
Applicability
(c) This AD applies to Model 390 airplanes, serial numbers RB4 through RB224, that are certificated in any category.
Unsafe Condition
(d) This AD results from nine occurrences of hydraulic fluid leaking from the engine hydraulic pump output fitting as a result of an improperly installed elbow connecting the output port to the pulse dampener hose. We are issuing this AD to prevent hydraulic fluid leaking from the left and right hydraulic fluid pump and to prevent the flow of hydraulic fluid into the engine compartment. The loss of hydraulic fluid can result in loss of airplane hydraulic system pressure and the consequent loss of hydraulic system functions including gear extension/retraction, spoiler functions, and antiskid braking system actuation. The inability of the hydraulic installation to isolate flow of hydraulic fluid could result in a hazardous amount of flammable fluid in the corresponding engine compartment. These conditions, if not corrected, could result in loss of system functions and/or fire in the engine compartment. Compliance
(e) To address this problem, you must do the following, unless already done:
Actions Compliance Procedures (1) Remove current preformed Within the next 200 Follow Hawker packing (part number (P/N) hours timein Beechcraft MS287786), elbow fitting service (TIS) after Mandatory Service (P/N MS21908J6), and jam the effective date Bulletin SB 29 nut (P/N AN9246J) from the of this AD or 3869, dated January left and right hydraulic within the next 6 2008.
pump pressure output port months after the
and install new preformed effective date of
packing (P/N MS287786), this AD, whichever
union (P/N MS21902J6), and occurs first.
swivel fitting (P/N
NAS1762J0606) in the left
and right hydraulic
pressure pump output port.
(2) Install hydraulic pump Within the next 200 Hawker Beechcraft case drain check valve Kit hours TIS after the Mandatory Service No. 39058030001. effective date of Bulletin SB 29 this AD or within 3851, dated January the next 6 months 2008.
after the effective
date of this AD,
whichever occurs
first.
Alternative Methods of Compliance (AMOCs)
(f) The Manager, Wichita Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to

FOR FURTHER INFORMATION CONTACT Anthony Flores, Aerospace Engineer, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Wichita, Kansas 67209; telephone: (316) 9464174; fax: (316) 9464107.