Please note the Nov. 23 proposed mandate for fuel tank inerting.
Electrical system safety: Extension of comment period -- Relates to advisory circulars (ACs) published concurrent with Electrical Wiring Interconnection System (EWIS) ruling
Nov. 8 FR Doc 05-22250
Extends the comment period for the EWIS draft ACs from Dec. 5th and 19th to Feb. 3, 2006, thereby making those comments due the same time as commentary on the basic rule. This is important, as 12 draft ACs apply, and the proposed rule must be evaluated in light of what the ACs have to say.
Electrical system safety: Final rule -- Boeing B727 airplanes
Nov. 8 FR Doc 05-22214 Docket No. FAA-2005-21975 AD 2005-23-07
Prohibits resetting a tripped circuit breaker for a fuel pump. Results from design reviews of fuel system safety (see ASW, July 11).
AD effective Dec. 13.
By this action, the Federal Aviation Administration (FAA) is seeking to prevent ignition sources inside fuel tanks. By separate action, outlined below in the Nov. 23 entry below, the FAA seeks to contain the hazard posed by flammable vapors.
Engine strut safety: NPRM -- Boeing B777-200 and -300 series airplanes
Nov. 9 FR Doc 05-22306 Docket No. FAA-2005-22874
Proposes corrective action to prevent cracking in aft fairings of engine struts, which allows engine heat to enter, degrading thermal/acoustic insulation blankets and the cracking can become a leak path for hydraulic fluid, which can lead to an uncontrolled fire in the engine strut area.
Costs estimated at $15,900 to $16,800 per airplane.
Affects 294 airplanes worldwide, of which 72 are in U.S. registry.
Comments due Dec. 27.
Aviation employee safety: Notice -- The FAA outlines random alcohol and drug testing parameters
Nov. 10 FR Doc 05-22398
The FAA has determined that the minimum random alcohol and drug-testing rate shall be 10 percent for alcohol and 25 percent for drugs for the period Jan. 1, 2006, through Dec. 31, 2006. This is based on current results of those who test positive well below these rates, which therefore are to remain in effect. No comment is invited.
Supplemental oxygen safety: Final rule, request for comments ? amended regulation
Nov. 10 FR Doc 05-22456 Docket No. FAA-2005-22915
Changes the flight level at which the remaining pilot must be on supplemental oxygen if the other pilot leaves his control station from "above flight level [FL] 250" to "above flight level 350." The FAA argues that this action will "reduce needless expenditures to replace oxygen equipment that is subject to excessive wear and tear."
Some commentators to the original 2004 proposal sought relief up to flight level 410. The FAA disagreed, saying:
"The FAA finds that FL 250 could safely be raised but an increase to FL 410, as requested, would not provide an acceptable level of safety. After reviewing the different TUCs [times of useful consciousness], the FAA finds that FL 350 is the highest FL that provides acceptable TUCs. The mean TUC at FL 350 is 34 seconds and the minimum observed TUC is 17 seconds. ... [This] is the shortest TUC to which the FAA can safely revise the affected regulation."
The new rule is effective Jan. 9, 2006. Any comments are due Dec. 27, 2005.
Fuel system safety: Final rule ? British Aerospace BAC 1-11 200 and 400 series airplanes
Nov. 16 FR Doc 05-22592 Docket No. FAA-2005-22427 AD 2005-23-15
Requires revisions to airplane flight manual and the maintenance program to prevent ignition of flammable vapors in the fuel system. Stems from SFAR 88 mandated review of fuel system safety (see ASW, July 11).
Cost estimated at $130 per airplane; 11 airplanes in U.S. registry.
AD effective Dec. 21.
This is one of a number of smaller airplanes listed in Appendix 5 of proposed AC 21.981-2A that are candidates for fuel tank inerting (see related Nov. 23 and Nov. 28 entries below).
Fuel system safety: Final rule -- Boeing B737-600, -700, -800 and -900 airplanes
Nov. 16 FR Doc 05-22593 Docket No. FAA-2005-21714 AD 2005-23-16
Requires modifying wire bundles above the center fuel tank to minimize potential for chafing and resulting arcing. Stems from SFAR 88 mandated review of fuel system safety (see ASW, July 11). Cost about $1,700 per airplane. Affects 1,636 airplanes in the worldwide fleet, of which 650 are in U.S. registry.
AD effective Dec. 21.
Fuel system safety: Final rule -- Boeing B737s
Nov. 16 FR Doc 05-22591 Docket No. 2004-19539 AD 2005-23-17
Requires one-time inspection and corrective action to fix chafed wiring and resulting arcing behind the P15 refuel panel.
Cost $195 per airplane. Affects 4,254 airplanes worldwide, of which 1,653 are in U.S. registry.
AD effective Dec. 21.
Cabin fitting safety:Notice of availability of proposed advisory circular (AC) and request for comments -- FAA publishes proposed update to AC 25-17A, "Transport Airplane Cabin Interiors Crashworthiness Handbook"
Nov. 16 FR Doc 05-22651
This long-anticipated update runs to some 200 pages and covers such topics as:
- Emergency exits.
- Emergency exit marking and lighting.
- Aisle widths.
- Seats, safety belts and harnesses.
- Ditching, and the provision of life rafts.
- Fire extinguishers.
- Acceptable procedures for flammability testing.
- Emergency evacuation and tests to demonstrate that all passengers can get out within 90 seconds.
As an example of the update, the draft AC includes the 16G seat requirement: "Peak floor decelerations must occur in not more than 0.09 seconds after impact and must reach a maximum of 16G."
And the AC recognizes the new reality of locked cockpit doors: "[I]f a lockable door is installed between the pilot compartment and the passenger compartment ... the emergency exit configuration must be designed so that neither crewmembers nor passengers need use that door in order to reach the emergency exits provided for them [for cockpit crews, egress would be via a cockpit window with a rope, described elsewhere in the AC]."
The AC recognizes the reality of lap children [e.g., dolls to simulate them in emergency evacuation drills] but it does not provide for their protection, which is solely oriented to adults, as in this section:
"Each occupant must be protected from head injury by
- A safety belt and shoulder harness that will prevent the head from contacting any injurious object;
- A safety belt plus the elimination of any injurious object within striking distance of the head; or
- Safety belts plus a cushioned rest that will support the arms, shoulders, head and spine.
- If the seat backs do not have a firm hand hold, there must be a hand grip or rail along each aisle to enable occupants to steady themselves while using the aisles in moderately rough air."
There is no comparable language applicable to lap children, for which the FAA has decreed that restraints are not required (see ASW, Sept. 12).
Regarding cabin furnishings, the AC says they must be self-extinguishing, which includes seats, carpets, sidewall and ceiling panels. However, the AC does not appear to enjoin against glass partitions and their potential to shatter under the heat of a fire.
The proposed AC is an update of AC 25-17 published in 1991 and presently in force, and another revision from 1999 that never went beyond the comment stage and is now the purpose of the revived filing.
Comments on the draft AC are due March 16, 2006.
Cabin fitting safety: Final rule -- Boeing B767-200 and -300 airplanes
Nov. 21 FR Doc 05-22791 Docket No. FAA-2005-20357 AD 2005-23-19
Requires reworking hinges to overhead stowage bins to prevent the bin doors from breaking or not latching correctly, raising the specter of the doors opening, spilling the bin contents, and blocking the aisles during an emergency evacuation.
Costs about $155,800 per airplane. Affects 172 airplanes in the worldwide fleet, of which 75 are in U.S. registry.
AD effective Dec. 27.
Structural safety:Notice of Proposed Rule Making (NPRM) -- Raytheon 58P and 58TC airplanes (a firefighting airplane, equivalent to the Beech 58 Baron)
The 58P/TC airplanes are used to pinpoint fires for the application of fire retardant, as from the old Douglas plane in the background. Photo: http://www.dynamicaviation.com/fire.htm
Nov. 22 FR Doc 05-23055 Docket No. FAA-2005-21175
Establishes a structural life limit of 4,500 hours, a reduction from the previous FAA-approved 10,000 hour life limit. These airplanes are used by the U.S. Forest Service (USFS) as lead airplanes in the firefighting mission. Recall that the airplanes actually dispersing fire retardant have the same problem, and two aircraft have had their wings separate from fatigue cracking under the unusual stresses of this mission (see ASW, Dec. 9, 2002).
The FAA says:
"Operation in the lead airplane firefighting mission is a more severe usage than the normal usage of twin-engine aircraft. ...
"The FAA has determined that if flight operations continue beyond 4,500 hours TIS [time in service], then the cumulative fatigue damage on these airplanes will reach a point at which fatigue cracking might occur. This damage will reduce residual strength and deplete all useful service life.
"Operation of these airplanes in a severe fatigue-loading spectrum accelerates the cumulative fatigue damage. This higher fatigue damage accumulation rate experienced by the USFS ... is higher than normal usage and results in a shorter life limit. The severity of the usage by the USFS reduced the structural life limit.
"The Service Difficulty Reports (SDR) database indicates some wing skin cracking, pressure bulkhead cracking, and cracking in both the vertical and horizontal stabilizers. A significant number of these cracking occurrences were on the subject airplanes. We believe that the SDR database does not reflect all such occurrences on the subject airplanes."
Cost about $65 (to input new service life into the airplane flight manual and other documents).
Affects 21 aircraft used by the USFS.
Comments due Jan. 23, 2006.
Fire protection:Notice of final policy -- Smoke penetration
Nov. 22 FR Doc 05-23016 Policy Statement No. ANM-03-112-06
FAA announces final policy on smoke penetration from a below-deck cargo compartment into the passenger cabin. In the policy memorandum, the FAA says:
"It is reasonable to expect that a small quantity of smoke may penetrate occupied areas during ventilation system transients or other perturbations in the airflow that may occur ... transients occur during changes to system configurations such as pack shut-down, fan shut-down, [and] changes in cabin altitude ...
"The term 'transient' as used herein refers to that period of time during which modulation of some component of the airflow management system (e.g., a valve, a fan, etc.) could lead to a short term change in the flow of the interior pressurized vessel, resulting in the entrance of smoke into the cabin. Similarly, it is reasonable to conclude that a small quantity of smoke that penetrates into an occupied area before the ventilation system is reconfigured in the event of fire detection would be acceptable under certain conditions. Small quantities or 'wisps' of smoke may penetrate the occupied areas as long as the situation represents a dynamic event with dissipation (i.e., are rapidly diluted by the ventilation air) or mobility (i.e., quickly enters and exits the occupied area).
"In no case, should there be a formation of a light haze indicative of stagnant airflow, as this would indicate a failure of the ventilation system to meet ... requirements.
"The small quantity of smoke that penetrates must not rise above the armrest height of the seat for passenger airplanes. This height was selected because it approximately represents the head level of a small child or infant held on the lap of an adult."
In its comments on the proposed policy, American Airlines said that a separate flight test should not be required:
"Smoke penetration testing can be part of a flight test plan for smoke detection, thus reducing the required number of test fights."
The FAA response is worth citing in full:
"[I]n practice different smoke combinations are required in the compliance demonstrations for smoke detection versus smoke penetration. For example, during smoke detection testing (i.e., to demonstrate that a cargo compartment fire can be detected within the 60 second time frame) the initial condition is 'no smoke' in the compartment. An acceptable smoke source begins to produce smoke (at time = 0) and the smoke detection system must alarm within 60 seconds.
"This is in contrast to a smoke penetration test where a certain amount (i.e., concentration) of smoke must be present at the start of the test (i.e., at time = 0). Of course, FAA would consider an applicant's proposal to perform a single test but actual testing would represent a challenge."
Final policy effective Nov. 4.
Airmen identities and confidentiality:Policy statement -- Accident and incident data system (AIDS)
Nov. 22 FR Doc 05-23101
Relates to general aviation and the AIDS database. The FAA says:
"From 1996 until the present, the FAA has expunged the identity of airmen from AIDS records on an ad hoc basis, where it was determined that their identity no longer served a relevant purpose. ...
"Absent a request for correction of records under the Privacy Act, the record remained in AIDS indefinitely. There has been growing concern within the FAA that this practice is unfair to those airmen who do not know their identity may be removed from an AIDS record by making a request under the Privacy Act. ...
"It is believed that after five years, any information about an individual's identity will be of little, if any, value. Under this expunction policy, any information which identifies the individual will be removed from the AIDS record, including the individual's name and FAA certificate number. The case report number will not be removed, nor will the rest of the information, such as the pilot's experience, the description of the event, the N number and type of aircraft involved. This information will be maintained so that the FAA will be able to research the accident history of an aircraft or conduct statistical research of data. ...
"The FAA currently has several decades of records which will be expunged under this policy."
The policy is effective Nov. 22.
Insulation blanket replacement:NPRM, reopening of comment period -- Concerns replacement of polyethyleneteraphthalate (PET) insulation blankets, also known as AN- 26, on Boeing B727-200, B737-200 through -400, B747-100 through -400, B757-200, and B767-200 and -300 airplanes
Nov. 23 FR Doc 05-23153 Docket No. FAA-2005-20836
Reopens comment period for 90 days on FAA's proposal to replace AN-26 thermal/acoustic insulation blanking in hundreds of aircraft. The AN-26 material can contribute to the spread of a fire. The FAA says:
"It is our intent to address the identified unsafe condition in a timely manner, with minimum disruption to industry, and maximum flexibility in methods of compliance. We encourage interested parties to continue to evaluate the proposal and to submit additional comments with more specific details concerning issues that the FAA may need to evaluate before finalizing its decision on the proposal."
The National Air Transportation Association (NATA) was part of an industry group that requested the extension. In a statement, NATA said:
"It has long been understood that the requirements of the final rule, titled 'Improved Flammability Standards for Thermal/Acoustic Insulation Materials Used in Transport Category Airplanes; Final Rule,' would apply to thermal and acoustic blankets installed in Part 121 aircraft as a result of the Swissair 111 accident in 1999.
"However, the FAA did not release corresponding guidance material for the regulations until June 24, 2005, in the form of Advisory Circular (AC) 25.856-1. As a result of that guidance, it became clear that the rule was being applied to every insulating material in the fuselage of every Part 25 aircraft (both old and new) to include hard components, wiring bundles, tape, hook and loop fasteners (Velcro) and every piece of installed equipment with insulation. This also includes microwave ovens, coffee makers, wiring sleeves, air ducting, avionics components and many other commercial-off-the-shelf pieces of equipment that contain insulation subject to this rule. ...
"The industry pointed out that the AC clearly exceeds the scope of the original rulemaking that specifically referred to insulating blankets, not the many piece parts within an aircraft that happen to contain insulation.
"Further, the economic impact analyses did not accurately evaluate the impact of the rulemaking on the industry and the substantial costs that would be incurred in order to comply with the standards prescribed in the AC."
Clearly, controversy abounds.
This is the second extension of the comment period. Comments were originally due June 3, but were extended to Aug. 3 (see ASW, June 13). Comments are now due Feb. 21, 2006.
Landing gear safety: Final rule, request for comments -- Airbus A310-100, A319-100, A320-111 and -200, and A321-100 and -200 airplanes
Nov. 23 FR Doc 05-23154 Docket No. FAA-2005-23087 AD 2005-24-06
Requires operators to check the nose landing gear (NLG) upper support arms, which may have been improperly connected after installation of a certain type of braking and steering control unit (BSCU). Relates to the Sept. 21 landing of a JetBlue A320 with the nose landing gear rotated 90 degrees to the aircraft centerline (see ASW, Sept. 26).
The Civil Aviation Safety Authority (CASA) of Australia issued a comparable AD on the same day; unlike the FAA, CASA characterized the action as urgent. The FAA, however, called for the "immediate adoption" of the AD. The CASA description of the Sept. 21 incident is the better of the two:
"Investigation showed that the upper support of the NLG shock absorber was damaged and the anti-rotation lugs were ruptured. This led the nose wheels to lose their centered position reference normally ensured by the shock-absorber cams. The BSCU had logged a steering system fault, because hydraulic power was not available at the time of the steering system checks, therefore the BSCU was not able to proceed with the re-centering of the wheels."
Both the FAA and the CASA ADs introduce operational procedures and maintenance actions.
The FAA describes its actions as interim, as the investigation into the JetBlue incident is still ongoing. Note that there may have been seven (or more) incidents reported where the nosewheels of the A320 were jammed at a 90-degree angle.
The FAA does not delineate the costs or the number of aircraft affected.
Comments to the FAA action are due Nov. 30.
Fuel tank safety:NPRM -- The FAA lays out procedures for ensuring the safety of heated center wing tanks (CWT)
Nov. 23 FR Doc 05-23109 Docket No. FAA-2005-22997 Notice No. 05-14
FAA proposes the means to reduce the possibility of an exploding CWT either through a Flammability Reduction means (FRM), which takes the form of inerting, or an Ignition Mitigation Means (IMM), such as filling the fuel tank with a fire/explosion-suppressing foam, which would confine a burgeoning explosion to a very small area.
This nearly 90-page NPRM and the associated advisory circular (see Nov. 28 entry below) is the latest development in ensuring fuel tank safety. The 1996 explosion of the CWT on TWA Flight 800, a B747, spawned a host of activity to assure the safety of fuel tanks, including a special design review to identify ignition sources under SFAR 88. However, this latest development seeks to blunt the second leg of the so-called "fire triangle," meaning the combination of an ignition source, the presence of flammable vapors, and fuel for the fire/explosion. SFAR 88 was aimed at reducing ignition sources. This action recognizes that eliminating all ignition sources is not possible (e.g., "We have concluded that we are unlikely ever to identify and eradicate all possible sources of ignition."), and therefore action is necessary to reduce the presence of flammable vapors. In this NPRM, that takes the form, principally, of an inerting system, which would fill the ullage space in the tank, or that space between the fuel line and the top of the tank, with nitrogen enriched air. By this means, the "atmosphere" within the tank would be too lean to sustain a fire or explosion.
In announcing this NPRM, FAA Administrator Marion Blakey said, "This proposed rule is the next step to close the book on fuel tank explosion."
"We're proposing to increase the level of aircraft safety by reducing the potentially explosive ingredient of flammable fuel vapors," she said.
"Reducing," not "eliminating" the threat of explosions, as recommended by the National Transportation Safety Board (NTSB), is the operative term. There is much in the NPRM worthy of comment, as a proper assessment of its impact lies between what it says and doesn't say.
The proposed rule applies to the existing fleet of large transports and new-production versions, but not all. The dividing line here is whether or not they have heated CWTs, such as air conditioning units located underneath the tanks, whose heat from operation can pass into the tanks, warming the ullage and creating the conditions ripe for an explosion if ignition occurs from a failure (such as an electrical arc or heat generated by a fuel pump impeller rubbing on the pump wall).
Aircraft without heated CWTs, such as the DC-10 and MD-11, which have their air conditioning packs located elsewhere than under the CWT, are exempt. The proposed rule applies principally to Boeing models, but includes the AirbusA320 and A330, as well as numerous smaller aircraft (about 18 other manufacturers). About 3,800 existing aircraft are affected.
An additional number of new-production aircraft are also affected. The rule basically affects all planes carrying 30 or more passengers in Part 121 (regularly scheduled) service. Part 135 on-demand operators are excluded, on the grounds that Part 135 aircraft are generally of 10 passengers or fewer in capacity.
Manufacturers must demonstrate that, on average for the fleet, the exposure of heated CWTs is equivalent to the present for wing tanks, which is to say no more than 7 percent of the operating time. A more demanding standard of 3 percent average flammability exposure is mandated for tanks within the fuselage contour and normally emptied during the course of normal flight operations (which includes unheated CWTs).
Cargo planes are exempt, on the grounds that the cost of installing an inerting system is not considered worth the expense (although SFAR 88 will apply, maintaining the current assault on identified ignition sources). Moreover, cargo planes don't fly as much as passenger planes, and they tend to fly at night, when the ullage is cooler. Thus, one explosion every 60 million miles over the next 50 years (the FAA estimate of the frequency of fuel tank explosions absent this proposed rulemaking) is not applicable to cargo planes, which are expected to accumulate just 23 million miles during this period. Of interest, the FAA talks in the NPRM about the number of lives potentially lost on the new double-deck A380 (which is being built with an initial capacity of 550 passengers), but since this airplane will not feature a heated CWT, it is exempt. However, a cargo version of the A380 will feature a CWT, and the manufacturer must show that it meets the 3 percent criterion, according to the NPRM (because of the slight added cost of equipping newly- built cargo airplanes with inerting, although this technology is not required for the passenger version, which would help to amortize costs).
The idea is to save passengers lives, which amount to $3 million to $5 million per life, according to the FAA, thereby satisfying the test of cost-benefit. The FAA estimates the initiative will cost $1,717 million and will save as much as $2,600 million in lives and aircraft lost. However, this positive cost-benefit is based on a host of assumptions. When those assumptions are varied, the FAA derives a positive cost-benefit relationship in only 5 of 12 cost scenarios examined (for example, changing the presumed effectiveness of SFAR 88 from 75 percent to 25-50 percent shifts the cost-benefit calculation for inerting from negative to positive). As the FAA admits in the NPRM, "If the SFAR 88 effectiveness rate is 75 percent, the proposed rule benefits would not be greater than the costs for retrofitted passenger airplanes under any combination of discount rate and value of a prevented fatality."
Even the cost of the proposed inerting system may be open to challenge. About two years ago, the FAA claimed its breakthrough inerting technology -- the same kind as proposed here -- could be had for less than $100,000 per airplane. The costs, depending upon narrowbody or widebody aircraft model, are pegged in the NPRM at $140,000 to $225,000 respectively.
The operators seem to be the ones who will pay for the inerting kits needed for retrofit. For new-production aircraft, inerting will be part of the purchase price.
Other costs are even less well defined. For example, although they are hoped to be minimal, the maintenance costs of the inerting system appear to be a mix of undefined and optimistic. The membranes producing the nitrogen enriched air, for instance, are presumed to have an installed life of 10 years. However, it is not known if, as they age and may be fouled, they are able to produce nitrogen with the same efficiency or purity as when new.
Indeed, the FAA seems to be basing its argument on a best-case basis. It has stripped out the hazard posed by terrorist attacks, such as the one that caused the CWT explosion on the Avianca B727 that was downed in 1989, and it is ignoring more recent events, such as the abortive bombing by "shoe bomber" Richard Reid on American Airlines Flight 63, a B767, in 2001 (see ASW,July 22, 2002, and Aug. 12, 2002). Reed had positioned himself over the CWT, and his bomb may well have ignited flammable vapors therein had it gone off. The NPRM also ignores the clean-up costs if a bomb near or above the CWT in a cargo plane destroys the aircraft and distributes hazardous material, which cargo planes often carry, over an area, necessitating isolation and remediation.
Above all, the NPRM assumes that the ambient oxygen in the tank ullage must only be reduced to 12 percent, not the more demanding and traditional 9 percent figure. Twelve percent allows a weight and cost saving for the inerting system. The FAA says the 12 percent figure is based on military testing that showed "a high degree of protection from a fuel tank explosion when a 30-millimeter high explosive incendiary projectile shot into fuel tanks." Twelve percent, the FAA said, provides protection against vapor ignition at 11.5 percent.
In other words, no safety factor is envisioned. For example, in determining structural limits, the FAA requires a 50 percent safety factor above limit load (the highest expected in service) to a level called ultimate load. There is no equivalent safety factor applied to inerting.
Indeed, the FAA suggests that energy limiting technology, in the form of transient suppression devices, need not be installed on fuel quantity indication system (FQIS) wiring, as one means of offsetting the cost of inerting. Thus, there is no "belt and suspenders" approach to fuel system safety, although the source of the last three fuel tank explosions has not been precisely determined (only conjectured).
With these caveats in mind, the FAA used a so-called Monte Carlo analysis, involving assumptions about aircraft type, fuel loading, length of flight, and other parameters, to assess safety. These computer simulations determined that if nothing were done, the industry would expect nine fuel tank explosions over the next 50 years. The SFAR 88 activity to mitigate ignition sources would eliminate four fuel tank explosions, leaving five, of which inerting would eliminate four. The baseline on which the FAA bases the number of expected explosions has been criticized before (see ASW, March 31, 2003). Suffice to say that with inerting, no fuel tank explosions should occur, yet the FAA propounds that despite all the effort expended by this proposed rulemaking another TWA 800 loss occurs, and that the FAA expected as much. Since the results are based entirely on computer modeling, the one loss not prevented may well be the first in actual fleet service, creating a public and congressional groundswell to mandate inerting for all aircraft within two to three years, and not the stately program outlined in the NPRM to inert half the fleet within four years of type certificate (TC) approval, which means the first inerting system would be installed more than 10 years after TWA 800 exploded, and the last airplane would be inerted nearly 20 years after that fatal accident (in the NPRM, the FAA hails its "strict retrofit deadlines.").
The proposal applies to both U.S.-registered aircraft and that of foreign operators flying to and within U.S. airspace. Or at least, this much is apparent from the NPRM, which alludes to coordination with European regulatory authorities. Yet, in its cost-benefit summary, the NPRM says, "[F]oreign entities flying into the United States would not be affected by the proposed rule and would have a competitive advantage in competing for international business with U.S. domestic carriers."
The FAA determines that the cost disadvantage is worth it: "Based on the safety issues involved, we determined that these costs are acceptable to obtain the required level of air safety."
Overall, the NPRM:
- Applies only to aircraft with CWTs and underlying heat sources.
- It ignores fuel pump and wiring problems in wing tanks; recall the chafed wing tank wiring that led to the Mothers' Day grounding of B737s in 1998 (see ASW, May 18, 1998).
- It does not account for terrorist actions that could ignite flammable ullage in any fuel tank.
- It plays down the reduction in nitrogen-enriched air during descent, focusing instead on the initial phases of flight when the ullage vapors are warmer.
- Aircraft without any possibility of heated ullage vapors won't be required to equip with inerting.
- It provides no safety factor, but does allow a yet-to-be-specified out-of-service time under the minimum master equipment list (MMEL), in which the aircraft with flammable vapors will be permitted to operate.
Whether this closes the book on fuel tank explosions, per Blakey's characterization, is entirely a matter of interpretation.
Comments are due March 23, 2006.
Fuel tank safety:Proposed advisory circular (AC) -- FAA publishes draft AC 25.981-2A, "Fuel Tank Flammability"
Nov. 28 FR Doc E5-6531 (Note: this appears to be a duplicate of the Nov. 22 Federal Register, FR Doc 05-23100)
The draft AC provides guidance for compliance with new standards elucidated in the Nov. 23 entry above regarding fuel tank exposure to flammable vapors and the mitigation of same. Explains in detail the Monte Carlo method of determining fleet average flammability exposure, to include the fuel flash point, airplane cruise altitude, and the fuel tank thermal model, among other factors.
The document lists all aircraft of 30 or more passengers, or a payload of 7,500 pounds or more, affected by the guidance to limit flammable vapors. Significantly, the listing at Appendix 5 does not include Douglas-built products, whose air conditioning packs are not located under fuel tanks.
Comments due March 23, 2006.
Recorder safety: Notice of availability and request for public comment -- Minimum performance standards for data-link recorder systems
Nov. 28 FR Doc 05-23304
FAA makes available for comments its proposed Technical Standard Order (TSO) C-177 for data-link recorder systems. As the FAA said:
"Digital messaging technology created a need for a data-link recorder system that would ensure the information and data necessary for the investigation of incidents and accidents continues to be recorded on-board the aircraft. It is important that these digital messages are properly recorded and that the timing correlation between cockpit displays and other aircraft systems are preserved. This proposed TSO prescribes the minimum performance standards for data-link recorder systems equipment necessary to receive, process, record, preserve, and retrieve Communication, Navigation, Surveillance/Air Traffic Management (CNS/ATM) digital messages transmitted to and from the aircraft to assist in the investigation of an incident or accident."
Comments due Dec. 28.
Source: U.S. Federal Register, see http://www.gpoaccess.gov/fr/index.html
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